NO. 10 TILLODONTIA — GAZIN 23

my

last notice of his discoveries."

There

follows his description of

Esthonyx

spatularius, Didymictis leptomylus,

and Hyopsodus

^speiri-

anus. Subsequently,

Matthew

_(1915, p. 314), ^{in his discussion of}

H.

speir'umus,

made

the following observations,

which

because of their importance in fixing the E. spatularius locality are quoted:

The type (Haplontyhts spcirianus) was originallydescribedwith other fossils as fromthe

Wind

River basin, but in 1885 the locality was definitely stated as Bighorn Valley. In cataloguingthe Cope Collection in 1896 I referred this dis- crepancytothecollector, Dr. Wortman,

who

informed

me

that althoughmost of his collections of 1880 came from the

Wind

River Valley andof 1881 from the Bighorn Basin, he did obtaina few specimens in 1880 fromthe Bighorn which were atfirstwrongly supposedby Professor Cope^tohave comefromthe

Wind

River Valley, the error being subsequentlycorrected. I citethese circumstances, because later collecting indicates that this genus is wholly limited to the lower part of the Wasatch, and is a valuable horizon-indicator (leitfossil). This is

equally true of Didymictis leptomylus, describedin the same notice as H.speiri- amis, as fromthe

Wind

River.

Matthew

did not

mention

the first of the three species, E. spatu- larius, described inthe

same

notice,

and what

appears to be a lapsus calamiinCope's "Tertiary Vertebrata,"in

which

E.spatulariusiscited as

coming from

the "Basinof the

Big Horn

River," is the

emendation

referredto

by Wortman

(in

Matthew).

This

was

applied in the

"Ter-

tiary Vertebrata" to each of the three

forms

included in the 1880 notice cited above.

Cope

also includedthe correct information

on

his specimen label for E. spatularius, although

Matthew

does not appear to

have

followed

up on

^this with regard to his

new

^{specimen label}

after his discussion with

Wortman.

Speculating

from

here, it

seems

probable that

Wortman

obtained the three specimens

from

about the

same

locality

and

horizon, inas-

much

as a collector of

Wortman's

experience would, in these beds,

have

obtained

much more

material

had

he at that time extended his examination over

any

appreciable area.

Two

of the species

Matthew

has

shown

are lower

Gray

Bull,

and

such

an

assignment forE. spatu- lariusisentirely compatible,

and

can be maintained

by much

the

same

evidence.

Among

the specimens tentatively

embraced by

the

name

E. spatu- lariusare the lower

jaw

(fig. 5of thispaper),

A.M. No.

16065,

from

the Clark

Fork

beds,

which Simpson

figured as

Esthonyx

fhisulcatus (1937, ^{fig. i) ;} three

Sand

Coulee specimens, including

A.M.

Nos.

161

44 and

168735

^"^

^

^^w

fragmentary,

unnumbered Gray

Bull specimens in the collections of the

American Museum. There

is,

moreover, a single, decidedly small specimen in the

U.S.N.M. New

Mexico

collections.

No.

17156, consisting of a

jaw fragment

with

M3

24 SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL. 121

which

has the

same

dimensions as the type of E. spatularius. Its di- mensions are approximately 18 to

20

percent less than for the E. bi- siilcatiis type, whereas the types of the invalid speciesE. acer

and

E.

hiirmeisteriiareroughly

4

^percent

and 8

to 10percentsmaller, respec- tively.

However,

the small size of

No.

17156 is even less significant in the

New Mexico

collections than the proportions of the type of E. spatularius are in the

Gray

Bull population,

inasmuch

as

mean

^for

the

New Mexico

material is

somewhat

lower.

The

Clark

Fork

specimen included in the above tentative assign- ment,

and

toa certain extent thetype,exhibitan almostintangiblecon- dition,

more

distinctive in the large E. grangeri

from

the

same

beds,

i.e.,a

somewhat

inflatedor

more

circularappearanceof thecusps than in

Gray

Bull materials, a condition, of course, not reflected in the statistical analyses of tooth lengths. This probably representsa

more

primitive condition of Esthonyx, indicating a

more

bunodont, less crescentic tooth pattern in the ancestry. Possibly further collecting willdemonstratethatthe Clark

Fork

specimenrepresentsadistinctive species. It should be noted, however, that the third molars in

A.M.

No.

16065

^"d

the type of E. spatularius are

much more

alike than the drawings (figs.

4 and

5,

made

by different artists)

would seem

to indicate.

MEASUREMENTS INMILLIMETERS OFEstlwnyxSpatulariusSPECIMENS

A.M. A.M.

No. No.

4809 1606s

Clark

Type Fork

P2, anteroposterior diameter 4.2

P2, transverse diameter 2.5

Ps, anteroposterior diameter 5.3 6.0

P3,transversediameter 3.7 ^4-

1

P4, anteroposterior diameter 74^

Ml, anteroposteriordiameter 7-8

M2, anteroposterior diameter ^7-8

Ms, anteroposterior diameter ^8.8 9.4

a,approximate.

ESTHONYX ACUTIDENS

Cope, 1881 Text figures 6-8

Type—

Left

M2 and M3, A.M. No.

4807.

Horizon and

locality.

— Wind

River formation.

Wind

River Basin,

Wyo.

Specific characters.

—

^{Size distinctly larger than E.} bisulcatiis.

Ros-

trum more

elongate

and

upper incisors relatively larger; P-

and

(in

NO. 10

TILLODONTIA — ^GAZIN

25

some

specimens) P2single-rooted,

and

P4

more

molariform. Parastyle

on

P*-]VP

and

metastyle

on P^-M-

well developed, with

cingulum

ex- tending

outward and forward from

themetastyle widelyflaring. Cin-

gulum on

anterior surface of talon reduced.

Upper

molars trans- versely broad.

Lower

molars elongate,

and

bases relatively broad as

compared

to width at occlusal surface. Talonid of

M3

comparatively elongate.

Discussion.

— The

type (fig. 6)

and

referred

upper

dentition

(A.M.

No.

4808, ^fig. 7^{of this} paper) oi E. acutidens described

by Cope do

nothaveaccuratelocalitydata otherthan

Wind

River Basin. It

seems

likely, however, that these are

from

the Lost

Cabin

^horizon. Sinclair

and Granger

(191_1,p. 104)^,in

naming

theLost

Cabin

beds, notedthat the

Lambdotherium

zone

had

previouslybeen

synonymous

with

Wind

Fig. ^6.

—

Esthonyx acutidens Cope: Left

M2

and

Ma

(A.M. No. 4807), type specimen, occlusaland lateralviews,

X

^{i- Lost Cabin}lower Eocene, Wyoming.

Fig. 7.

—

Esthonyx acutidens Cope: Right upper dentition (A.M. No. 4808), occlusal view,

X

^{i- Lost} Cabin lower Eocene, Wyoming.

River.

However

this

may

be, only E. acutidens has been certainly recorded

from

theLost

Cabin

beds,

and

material

known from

Lysite localities

may

include both E. bisulcatus

and

E. acutidens.

Among

the

more

significant specimens of E. acutidens, in addition to the

two

collected

by Wortman and

originally described

by

Cope, are the greater part of alowerdentition,

A.M. No.

14738,^collected

by George Olson on

Alkali

Creek

(Lost Cabin) ; skull fragments

and

part of theupperdentition

which

have been incorporatedinto a gener- alizedskull restoration,togetherwith

some

vertebrae

and

limbportions,

A.M. No.

_14735, collected

by Walter Granger on

^Alkali Creek;

and

a rostralportion of a large skull (fig. 8) including representation of all the

upper

teethexceptthe thirdupperincisor (or canine?),

U.S.N.M.

No.

18202,collected

by Harry

Tourtelot, of the

U.

S. Geological Sur- vey,inbedsidentified

by him

asLost

Cabin

inage.

Esthonyx

material collected

by

Patterson

from

the Plateau Valley beds in Colorado in-

26 SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL. 121