Meek and

185G.] ^..

63

Descriptions ofneic speciesof Gasteropoda

from

^theCretaceous formations ofXebraska Territory*

By

F. B.

Meek and

F. V. Haydex, M.^D.

The

species indicatedⁱⁿthe followingpaper comprisea portion ofanextensive collection recentlybrought from Nebraska hy oneof the authors. f ^{It is}

worthy

ofnote that

some

of the speciescontainedinthe collectionfromthemostrecent Cretaceous bedsoftheupper^Missouri country appear^referabletogenera which, according^tohighEuropean authority, datenofarther

back

thanthe true chalk, while

many

^of

^them

^{are closely} analogous ^toTertiary forms; so close indeed, that

had

_they not been found associated inthe

same

beds with

Ammonites,

Scaphites

and

other genera everywhere regarded ^as having

become

extinct at the close of theCretaceous _epoch,

we would

have considered

them

_Tertiary

species. Ifthesebeds _really are equivale^{it to}

any

portion of theGreen sand of English geologists, ^{it is} a curious 'act that

we

should find mingled together ^{in tlieni} upper Cretaceous

and

_Tertiary forms _exactly as if they

and

those of the older Tertiarywere_depositedinthe regular order ofsequence.

Such

facts

however

aresometimes

met

with

amongst

^Pahtozoicformations.

The

following section exhibits the order of superposition of theformationsin

which

our Cretaceousfossilswere_found,

and

theirrelations tothe Tertiary

and

older rocks.

Tertiary⁽Bedsof_clay,sandstone, lignite, &c.,containing remainsof vertebrata, 400to-! andatplaces, vast

numbers

of_jilants,with land, freshwater,

and

600ft.

(_ sometimes marineor estuary mollusca.

5

^

Gray and

_yellowish arenaceous _clays containing great

numbers

of marine mollusca with afew land plants. 100to 150feet.

4

-J Plastic clayswith

numerous ^arine

^mollusca.

About

350feet.

3 f

Gray and

yellowish ^calcareous

>

\

scales,^(fee. 100to 150feet.

marl, containing Ostrea_congesta, fish

u

2\ Grayish

and

lead colored clayshaving few^{fossils. 80feet.}

1/Si;Sandstones

and

clays not positively

known

to belong^totheCretaceous svstem. 90feet.

Limestones ofupper ^coal measures at Council Bluffs, containing Spirifer Meuscbachauus,

AUorisma

terminalis, Terebratula _subtilita, Fusulina _cylin- drica, &c.

ScALARiA CERETHiFORMis. Shell elougate-conical, turreted, not umbilicate;

volutionssevenor_eight,convex,closelycontiguous, traversedby numeroussharp, slightlycurved_cost*,lessthan_{the spaces}between; ^surface

marked

_byirregular

linesofgrowth,^crossed

by

fine,unequal,thread-like, revolvinglines,as strong onthecostte as

between them

; suture_distinct; aperture ovate,angular on ^the inner sideabove,rounded below:lipthin,curved

ontwardson

theinncrsidebelow.

Length

^1.G5 inches,breadth .73 inch

; length of aperture^.52 inch, breadth.40 inch; apicalangleslightlyconvex, divergence about

28.

Locality.

Moreau

_tradingpost. No. 5of the series, rare.

AcTEON

suBELLiPTicus. Shell elougate-oval or

narrow

_elliptical; spire some-

what

elevated; volutions about_four; surfsxcepolished,and ornamented by about twenty-five regularrevolving strite,

composed

^ofround punctfe so disposed as torange up and

down

theshellexactlyparallel totheobsoletelinesof growth;

suture_distinct;aperturenarrow,curved,acutely-angular on^theinnersideabove,

*Figures,comparisons,

and

remarkstobe published ^hereafter, fDr.Hayden.

[March,

gradually"widening

downwards

tonbontthe middle,from which _pointit again verygraduallj' contractstowards tlienarrowly ronnded^{front; ovitcr} lipthin;

columella havinga single small oblicjue fold,outside of

which

thereis a small umbilical groove. Length ^.25 inch, breadth .10 inch; apical angle regular, divergence

57.

Localityand_position.

Crow

Creek near Blackhills. No. 4 of the series.

AvALANA

SUBGLOBOSA. Shell globose ^or subovate

; spire very short, slopes

rounded

; volutions four,increasing rapidlyfrom theajjcx, lastone_{veiy large}

and

ventricose

; surfaceornamented

by

^aboutthirtypunctatestria?,half aswide as the elevations between on the upperpart of the volutions,but

much more

closely croAvded on the lower part of the ^last turn

; suture _linear, distinct

;

aperture semilunar,widest below,^contracted and terminating ^{in a} smoothly

rounded

_angleabove; outer_lipsmooth_{within,faintly}sinuatebelow and having a thick strongperistome without; inner_lipthickandraisedintoa singlepromi- nenttranverse toothbelow. Length^.39inch,breadth.37inch;length of aperture .21inch,breadth.11 inch.

Localityand_position^.

Moreau

_tradingpost. No. 5of theseries.

Natica?AJiniGCA. Shelloblicjuelysuboval, oroblong;spiredepressed-conical;

volutionsaboutfour, convex, increasing somcAvhat _rapidly fromthe apex,^last oneventricose; surface

marked

_by fine linesofgrowth and stronger parallel wrinkles, crossedbystrong irregular revolving^stri;\?;suture_distinctlyimpressed, aperture obliquely ovate,angular above, rounded below; lips thin,ajiparently disunitedabove andabrujitly deflected

outward

onthe inner side below the small orrudimentary ^umbilicus. Length.50 inch, breadth .42inch; length of aperture^.34inch, breadthofdo. .24inch; apicalangle convex,divergence

81.

Localityand^josilion.

Same

aslast.

Naticaoccidentalis. Shell obliquely-oval or ovate;spireelevated;volutions aboutfive,convex;surface

marked

with finelines ofgrowth, andfaintor nearly obsolete,minutelytiexuous revolvinglines; suture_distinctlyimpressed;aperture ovate, straightonthe insideand broadly rounded without;outerlipthin

; inner lipnot thickened, partly deflectedovertheedge of the small oblique umbilicus.

Length

^about.97 inch,breadth.70inch; length of aperture^.56 inch, breadth .33inch; apicalangle convex,divergence

70.

Localityand_position.

Same

as preceding.

Natica Moreauensis. Shell obliciuely-ovate^; spire

somewhat

_depressed;

volutions threeanda half_{to four,}convex,^lastone_large

and

ventricose;surface

marked

)jyfinelines ofgrowth,^crossedbyA'eryfine,nearl;y obsolete,minutely flexuous revolving^lines; suture_distinctlyimpressed^orsub-channeled

; aperture ovate

; outer_lipthin; innerlipnotthickenedanddeflected partly over the small umbilicus. Length about ^.90inch, breadth .70 inch

; length of aperture ^.54 inch, lireadth^.36inch; apical angleslightlyconvex,divergence

90.

Locality andposition.

Same

as preceding.

TuBBO

Nebrascensis. Shell turbinate, lengthand breadth about_equal; spire broadly^conical; volutions aboutfive,ronnded, gradually increasing from the apex; surface ornamented

by

^finerevolving stria',crossedby ^{delicatelines of} growth,

becoming

^distinctoblique wrinklesalong^thesuture

and

roundthe

um-

bilicus,the whole_presentinganelegant cancellated appearance under^{a lense;} suture _distinctly impressed; aperture round; umbilicus moderate, round.

Length.25 inch,breadth.26inch; diameterof aperture^.12 inch; apical angle

somewhat

_{convex,divergence}

53.

Localityand_position. Yellow Stone_river,one

hundred

and _fifty miles from mouth. No.4 ofseries.

Turbo

tenuilineatus. Shell oblong ^or suboval, oblique, thin; spire some-

what

elevated, acute at tlie apex; volutions about five, rounded, increasing rapidlyfromtlie apex; ^lastone ventricose,extended infront

; surface

marked

1856.] 65

with distinct linesofgrowth,^crossed

by

rounded,thread-like lines, generally- less than the spaces between,

and somewhat

_irregular in size; between the latter there are also very ^fine parallel revolving strife, only ^visiblo under a lens, suture apparently canaliculate

; aperture broad ovate or oval

; outer lip thin; inner _lip straight above,

and

_distinctly curved outwards

below

at its junction withthe outer _lip near the small umbilicus. Length ^.84 inch, breadth.68inch; apical angle regular, divergence

78;

length of aperture^.50 inch,breadthof do..36inch.

Locality.

Moreau

_tradingpost. No. 5of theseries.

RosTELLARiA BiANGULATA. Shellelongated; spire elevated,acutely conical;

volutions seven or _eight, convex, ^crossed

by

^small nearly obsolete _folds, last one having

two

distinct revolving carin* on the middle,

which

_diverge

inpassing

upon

^the

expanded

lip,

and

terminate in

two more

or less saliant angles ^{at its}outermargin; surface

marked by

^fine very^{faint linesof}growth, crossed

by

^small revolving thread-like lines about equal ^the intermediate spaces, on_{the spire}

and

_upperpart of the^lastturn,but

more

distinctandalter- nating withsmaller onesonthelowerpart of the

body

^{volution; suture} linear, sharplyimpressed; aperture

unknown

;outer_{lip thin,}expanded,

and

_extending

more

or less up^the spire. Length^.53 inch,breadth exclusive of the_lip .21 inch

; apical angle regular, divergence^3'7.

Localityand_position. Yellow Stone_river,one

hundred and

_fiftymiles from mouth. No.4 of theseries.

FuscrsDakotaexsis. Shellfusiform

;spire conical,

somewhat

elevated; volu- tions about _si.x,flattened or concave _above,last one abruptly contracted into the canalbelow,

and ornamented

onthemiddle

by two

elevated revolvingnodose carinoe, between

which

_{faint,broadly rounded,} verticalfolds pass from node to node.

On

the_spire only the upper

and most

_prominentcarinais seen,while athirdlessdistinctparallelridgepassesround lower

down

onthe

body

^whorl;

whole

surface

marked by

fine, regular Huesof growth,^crossed

by rounded

^re- volving lines,oneof which, about

midway

^betweenthe

^two

large carint^, ^is strongerthanthe others; suture linear; aperturebroadoval or ovate.

Length

fromjunction of canal

and

_aperturetoapex ^1.03inches,breadth.92inch; length of aperture ^.48inch,breadth.42 inch; apicalangle regular,divergence

51.

Locacity

and

_position.

Moreau

_tradingpost. No.5of theseries.

Fusus

Galpinianus. Shell small, fusiform; spire conical, acute

; volutions five

and

a halfto _six, convex, ^last one_sloping

somewhat

_abruptly

below

into the short canal;surface

marked by

^{fine flexuous lines of}growth, ^crossed

by rounded

little revolving bands or lines scarcely larger thanthe grooves^be- tween.

About

fourteen of thesebands

may

^{becountedonthe second}volution;

suture distinct; aperture narrow-oval, acutely angular behind,

and

_sloping intothe canalinfront

; outer_lipthin

and

_sharp; inner _liplying close

upon

^the tortuous columella. Length^1.05 inches,breadth .42 inch; length of aperture (including canal) ^.53 inch,breadth.18inch; apical angle regular or slightly convex, divergence

32.

The

above_speciesisdedicatedto Mr. C. E. Galpin, of

Am. Fur

Go.

Localityand_position.

Same

aslast.

Fusus

coNTORTDS. Shell obliquely fusiform; spire elevated conical, acute at the apex; volutions^five

and

a halfto_six,distinctlyconcave_above,convex below,

and ornamented by

^{indistinct flexuous} folds,

which

swell out into a

row

of prominent nodes round^the middle; last volutiongraduall}'- contracting

below

into ashort canal

; surface

marked

_byfine flexuous linesof

growth

^crossed

by numerous

elevated thread-like revolvinglines,alittleless thanthe spaces be- tween;suturedistinct

;aperture ovate,widest abovethe middle,angularbehind,

and

_taperingforward; outer_lipthin

; inner _lipclosely folded

upon

^{the some-}

what

tortuous columella.

Length

^{about .90} inch, breadth .48inch; length of apertureandcanal.56inch,breadth.20inch; apicalangleconvex,divergence

45.

Locality.

Same

asthe preceding.

[March, Fnsus

CcLBERTSONi. Shell elongate fusiform; spireelevated conical, acute^; Tolutionsabout_seven,convex, increasinggradually fromthe apex,and crossed nearly^atrightangles^tothesutureby^sixorseven _strongrounded_folds,

which

gradually

become

obsoleteonthelastnearthe aperture; lastvolution tapering gracefully

and

obliquely into the canal,

which

is ofmoderate _length; surface

marked

_{by irregular} linesof growth, ^crossed

by

^{flattened or rounded} lines,

somewhat

_larger than the spaces between; suture _distinctly impressed,

and when

viewed fromaVjoveis seentodeviate from _{a regular} curve in following the

waving

^{outlineof the folds;} aperture lanceolate or

narrow

_{oval, acutely} angular above

and

_{taperinggradually}below. Length about1.68 inches,breadth .50inch

; length of aperture

and

canalabout.90inch,breadth .23inch; apical angle convex,divergence

28.

We

dedicatethisspecies^toMr.AlexanderCulbertson, of the

Am. Fur

Co.

Localityand_j^osition.

Same

as preceding.

Fusus

FLEXUOCOSTATDS. Shell fusiform; spire

somewhat

elevated, acute at theapex^{; volutions six to six}

and

a _half,convex, traversedby strong, simple, flexuous folds nearlyequalling the spaces between, and terminating above ⁱⁿ gmallnodes so astoleave ashallow_spiralgroove belowthe suture; ^last whorl

somewhat

ventricose; surface

ornamented

_by distinct linesofgrowth,^crossed

by

snirtll,elevated, thread-like,revolvinglines,equal the spacesbetween onthe upperpart of the volutions,but

more

distantonthelowerpart of the^lastone;

between

the revolving^lines

and

_parallelwith them,^finestriie

may

^beseen

by

the aid of a magnifier; suture

unknown

; aperture oval or ovate.

Length

^1.05 inches,breadth .61inch;length ofaperture exclusive of canal^.48 inch,breadth .30inch; apical angle

46.

Localityand_position.

Moreau

river. No. 5ofseries.

Fusus Newbekrti. Shell fusiform, thick; spire conical; volutions five, flattened orconcave _above,convex below

and

ornamented round the middle witha

row

of

more

or less prominent nodes,

which

are sometimes prolonged on the lastoneinto indistinct folds below; ^surface ornamented

by

irregular flexuous lines of growth, ^crossed byround, elevated, thread-like, revolving lines, sometimes _greater and sometimes less than the spaces between;

suture linear; aperturenarrow_ovate,angular above andscarcely^distinctfrom the short canalbelow; outer_lipthin orbevelled; inner_lipcloselyspread

upon

the columella.

Length

^1.43 inches,breadth.81 inch; length of aperture (in- cludingthe canal) ^.87inch,breadth .32inch

; apical angle convex, divergence

55.

We

^dedicatethisspecies^to Dr.J.S.Newberry,of Cleveland, Ohio.

Localityand_position.

Moreau

riverand

Fox

Hills. No. 5 ofseries.

Pyrula

Bairdi. Shellpyriform^; spiredepressed; volutions_five,rapidly ^in- creasingfromthe apex, flattened orslightlyconcave above

and

onthe outside;

lastone_largeandventricose,ornamented onthe outside

by two

^tothree

more

orlessprominent,revolving,nodose _{carina?,only the} upper^of

which

is visible onthespire; surface

marked

_bystrong linesofgrowth, ^crossedby

numerous

elevated revolvinglines, lessthan_{the spaces}between,

and

sometimes assuming, on^{the outer}and lowerpart of the^lastvolution, the^sizeof

more

distinct ridges;

suture narrow, channeled^; aperture ovate, abruptly ^{contracted into the} long- canalbelow; columellatortuous, and deeply curved roundthe aperture; outer lipbevelled; innerlipthinly spread over thecolumellaroundthe aperture,but leavinganumbilicalgroove about^half

way down

^{the canal.} Length3.50 inches, breadth.2 inches; length of aperture (including the canal)^.3inches, breadth 1.08inches; apical angle nearly regular, divergence

114.

Dedicated to Prof.Spencer^F.Baird, of theSmithsonianInstitution.

Localityand_position.

Same

as^last.

Fasciolaria cretacea. Shell small elongate, fusiform;spireelevated conical;

Tolutions^fivetosix, convex,^lastonealittle

more

thanhalf theentirelength of

1856.]

67

the_shell, contracted

below

into a tapering canal; surface

marked

withflexuoui lines of

growth and

^littleflatrevolvingbands aboutfourtimes aswideas the grooves between; suture distinct

; aperture

narrow

_oval, angular above

and

narrowing gradually below; columella tortuous

and

_havingfive small,oblique foldsnearthemiddleofthe aperture.

Localityand_position.

Same

as preceding.

Fasciolaria bcccinoides. Shell elongate-oval orsubfusiform; spire conical, acute; volutions liveto five

and

a_half,convex, ^last one

somewhat

veniricose

and

contracted below into a short canal; surface

ornamented

with fine regular ^lines of

growth and

small parallel folds,

which

are crossed

by

regular,round, elevated revolvingbands,ecjual to or greaterthanthe spaces be- tween.

Of

thesebands aboutfourteen

may

^{becounted onthesecondvolution;}

suture_distinctlyimpressed; aperture narrow,oval,or semi-elliptical; outer_lip faintlygrooved, and^{atintervalsof}about onceforeachturn

becomes

thickened

and

crenulatedonthe inside

; inner _lipcloselyspread

upon

^the tortuous columella,

and

_forming about the middle of the aperture

two

distinct oblique ^folds.

Length

^.96inch, breadth.49inch

; length ofaperture

and

canalabout.60inch, breadth .23 inch

; apicalangleconvex,divergence

54.

This shellhas

much

the general appearance^{of a}Buccinum^ having ^theform

and

surfacemarkings^{ofii.decussatum}

(Lamk.)

^{an Eocene}species fromtheParis basin,butdiffersfromthe genus Buccimim ⁱⁿhaving

two

distinctfdds on the columella,being^{in this}respect

more

likeFasciolaria.

The

foldsonthecolumella arc not _stronger, however, than

we

see in B._fusiformis of Deshays, another Tertiary species.

We had

once concluded to referit with doubt to the

genus

Bticcinum,butreferittothegenusFasciolaria,atthesuggestion^{of Dr.}Gould,^to

whom we

sentspecimens. This genus, according ^toD'Orbigny,

made

its first

appearance^{inthe old}world duringthe deposition of the true chalk.

Localityand_position.

Moreau and Fox

Hills. No. 5of theseries.

BncciNUM

^?Nebrascensis. Shell_oval,thin; spirevery^short;volutions three tothree

and

a_half,convex,rapidly increasingfrom_{the apex,}lastone verylarge

and somewhat

ventricose

; surface

marked

with distinctlinesof growth,

which

are crossed

by

flattened,revolving bands,

much

wider ontheupper part of the volutions than the shallow grooves between, but about equal^to

them

on the lower part of the ^last turn.

About

seven or eight oftiaese bands

may

^be counted onthesecondvolution; suturenarrow, channeled; aperturelarge, sub- elliptical,angular above,

and

terminating^inarounded notch_{in front,}theformof

which

iswell defined

by

^a

sudden

curveinthelinesof

growth

^onabroadspiral ridgeroundthe outeredge^{of the}pillarlip;outer_lipvery^thin;innerlipthinly spread over the extremely tortuous columella.

Length

^.77 inch,breadth .58 inch; length of aperture ^.61 inch,breadth .36inch

; apical angle convex, ^di- vergence

105.

Beingⁱⁿdoubtinregard^tothe generic re'ations ofthis shell,

we

sent speci-

mens

ofit,

and

afew_others,tothe distinguished conchologist. Dr.

Augustus

^A.

Gould,of Boston,from

whom we

leceivedin legard^toit,the followingremarks:

"_Its

general form reminds one_{of Naiica,}

and

itsrevolving^{striaeof the}subgenus Naticina. If

we

lookatthe base,however,

we

finda revolving ridge

which

is

never foundinthe Naticidae,butispeculiar^to the

Buccinid."

Dr. G. further remarksthatwiththe exception of the revolving^strijeitagreesverynearlywith the genus^Pseudolieaot Swainson,

which

isnot

known

to datebackfurtherthan theEocene. In

many

respects ^it resemblesthe

Eocene

Buccimim. ohtiisum of Deshays, fromthe Paris basin,

which

formsthe type ofanEocene genus ^estab- lishedby D'Orbigny under^the

name

of Sulco huccinum.

Our

shell has_{the form,} revolvingstrife, &c., of

some

_{species of}D'Orbigny'sgenus,butwantsthestrong revolving sulcus,

which

isoneof itsprincip.ilcharacters. Forthe_pres'-nt

we

referittothegenus Buccinum, though

we

_suspectit

may

^formthe type of a

new

ge^nns.

Locality

and

_position.

Same

aslast.

[March, Capulcs

feagilis. Shellbroadlyconical,very^thin; apex elevated, central;

slopesslightlyconvex,divergence⁸⁰ ;surface

marked

with_fine,closely arranged, concentric stria3

; aperture ^circular. Diameter of base 1.21i inch; height ^of apex about^.74inch.

It iswith

some

doubt

we

refer thisspecies^totheabove_{geaus, as}our specimen only consists of an internal castwitha few fragmentsof shell adhering; no muscularimpressions are^visible uponit,butthe_{nipjile at}the

summit

_appears

tohave occupied^{theinteriorof}an attenuated

and

_laterallycurved_apex.

Localityand_position.

Fox

Hills. No. 5 oftheseries.

Genus IIELCION

(Montfort).

We

have not_yet

had

an opportunityof seeing the ^interiorofany^{of thefol-} lowing patelliform shells, but,judging from ^external characters,they appear referableto the above genus^{as defined}

by

D'Orbigny.

They

^areall strictly symmetrical,with, as^farascan beascertained,thin,smooth,

and

_nearly, ifnot quite entire borders.

Helcion sexsulcatus. Shell patelliform, longer than wide; apex

between

the centre

and

anterior margin depressed; lateral slopes nearly straight, di- vergence

100;

anterior slopeslightlyconcave,

and

_having

two

broad shallow grooves radiating from the apex ^to the antero-lateral edges; posterior slope convex,

and

_havingfourbroad shallow groovesradiating fromthe apex^{to the} posterior

and

lateraledges; baseor aperture oval; surface

unknown.

_Length

unknown,

breadth about1.29 inch,height ^.48inch.

Localityand_position. Yellow_Stone,one

hundred and

_fiftymilesfrom mouth.

No. 4 of theseries.

Helcion patelliformis. Shell patelliform, thin,a little longer than wide;

apex

somewhat

elevated, nearer the centre than the anterior margin; lateral slopesnearl)^ straight,divergence about^{90 ;} anterior slope straight or slightly concave, posterior convex, divergence^ofthe

two

about103

; surface

marked

withfineconcentriclinesofgrowth,

which

arecrossedhj very^faintindications of.fineradiatingstriae,

and

onthe anterior side

by

^{three or} four scarcely per- ceptible, radiating^carinte(the ^latternotalwayspresent);aperture broad,^oval.

Length

¹inch,breadth.84inch,height^.44inch.

Localityand_position.

Same

aslast.

Helcion alveolus. Shell patelliform,thin,longer than wide;apexdepressed, nearly central; lateral slopes convex

and

forming an angle^{of 80} ; posterior

and

anterior slopesabout_equallyconvex,divergence

120;

^surface

^marked

^with very^{fine concentric lines of}growth; base or aperture ellipticalor subovate,

Length

.63 inch,breadth .43inch,heigh^{th .17inch.}

Localityand_position. Yellow Stoneriver. No.4 of series.

Helcion subovatus. Shell patelliform, longer than wide; apex depressed, situated abouthalf

way

^{between the centre}

^and

^{the anterior} margin; lateral slopes convex,

and

forming anangle of 80 ^; posterior slope

more

convex than the_anterior,divergenceof the

two 104;

^surface

^marked

by ^faint, irregular, concentricundulationsand imbricating^linesof growth; baseor aperture oval or subovate, extremities broadly rounded,the posteriorend being^alittlewider thantheanterior. Length1.16 inches,breadth .81inch,heighth.39inch

Localityandpositio7i.

Same

as preceding.

'!

Helcion carinatus. Shell very obliquely conical or bonnet-shaped, ^thin;

apex ^elevated near the anterior margin,

and

directed forAvard

; anterior and antero-lateral slopes profoundly concave; posterior slope convex above

and

flattenedorconcave below.

A

single strong,rounded carina passes from the apex

down

the posterior slope,

becoming

gradually^obsolete nearthe margin, while

two

orthree

much

fainterones radiatefrom the apex

down

the postero-

1856.] 69

lateralslopes on each side ofit. Sixsmall indistinct strife radiatefrom the apex,

two

of

which

are directedforwards

and

_ontwards,

and

four

backwards and

outwards;faint,irregular, concentricundulations dimlyindicate the progressive stages of

growth

^{; surface otherwisesmooth}; aperture ^circular. Diameter of

aperture^1.93 inches,heigh^{th of} apex^.80inch.

Locality

and

_position.

Same

as preceding.

Dentalium

fragilis. Shell very thin, slender,gently curved from npex ^to base

; surface

ornamented by

rounded, thread-like,longitudinallines,Avhich are crossed

somewhat

_obliquely

upwards

^{fromtheinnertotheoutersideof thecurve}

by

ver}' fineregular^linesofgrowth.

The

longitudinal^linesterminate abruptly alittle

below

_{the apex,}(where they

number

about _fourteen)and increase in

number

_byimplantation,

and

diminishin size

and

_regularitytowardsthe larger end, so as^to

become

nearly obsoleteon thelower half of theshell; aperture circular. Diameterattheapex ^.05inch, do. of afragment^.85inch,

below

_apex

.13inch, do. of largest fragment^.19 inch; thickness of ^{shell .02} inch; apical angle

3.

The

above_speciesisclosely^{allied to}D.gracilis,Hall

and

_{Jleek, (vol.}5,

new

series. Trans.Acad. Arts

and

_Sciences,Boston) but^{differs in}having

much

less prominent longitudinal striie,

and

not

more

thanhalf as thick ashell

; while the aperture,

which

inthe formeris nearlyalways subcircular,ⁱⁿthe present species^isexactly^circular.

Localityand_position. Yellow Stone_river, one

hundred and

_fiftymiles above mouth. No.4 of section.

Bulla

volvaria. Shell

narrow

ovate, tapering gradually from

below

the middle upwards,

and

extended _obliquelybelow; spire hidden, sometimes ura- bilicate

; surface

ornamented by

^{faint lines of}

growth and

shallow _revolving

striiB,about onefifthaswideasthespaces between onthemiddleof the shell, but

more

_closely

crowded and

irregular at the lower

and

_upper extremities.

Occasionally^a

much

finer striaoccupies oneof the spacesbetweenthe others;

aperture long, narrow, gentlycurved, risingabovethe

summit

of thebody, about half aswide abovethemiddleas

below

; lip thin,closely folded overthe rudi-

mentary

^umbilicus.

Length

^.66inch,breadth .36inch.

Loccilityand_position

Moreau

_tradingpost. No.5of section.

BcLLA

MINOR. Shell minute,ovate, or _elliptical; spire hidden, umbilicate;

surface

marked by

elevated,sharp, revolving strife,about _equal to the grooves

between

;finesharply^{elevatedlines of}growth,

more

distinct in thegrooves than onthe elevations,

mark

the surfaceintheother direction; aperturelarge,rising abovethe

summit

of thebody,

narrow and

obtuse above,

and

widening gradu- allybelow. Length about^.10inch,breadth.05.

Localityand_position.

Moreau

_tradingpost. No. 5of theseries.

Bulla

occidentalis. Shelloval or ovate,thin,ventricose,widestalittleabovethe middle,

rounded

atthe

summit and somewhat

_obliquelyextended infront; spire hidden, umbilicate; ^surface

unknown.

Indistinctlines of groAvth,

and

_stronger revolving ^{striae less} thanthe spaces

between

are seen

on

the cast; aperture curved,

narrow

_behind,risingabove^the

summit

ofthe_bodj^,

and

wideningcliiefly onthe inner sidebelow; lipslightly curved outwardsround thelower_{part of} the aperture. Length ^.44inch,breadth .28inch.

Localityand_position. Yellowstoneriver. No.4 oftheseries.

"Wehaveother

new

_{species of} Gasteropoda from^theCretaceous formations of theupperMissouri,butrefrainfrom _indicating

them

out of deferenceto friends having specimens^{of the}

same which

they wishtodescribe.