PROCEEDINGS

Vol. 32, pp.213-216

December

31, 1919

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

TWO NEW CROTALINE SNAKES FROM WESTERN MEXICO.

BY

E. R.

DUNN.

Among ^the many

reptiles

brought back from Mexico by Nelson and Goldman were

three

small

_snakes,

two

rattlers

and a

Lachesis.

The two

rattlesnakes are

obviously

^alike

and appear

to

be unnamed. So

likewise

the

Lachesis

seems

to

be

hitherto

unknown.

In naming

^these

new snakes

after

Dr. Stejneger and Dr. Bar-

bour. ^I gladly

take advantage

^of

an opportunity

^to

show my

appreciation

^of

the advice and encouragement which they have

sooften

given me.

Lachesis barbouri,sp. nov.

Diagnosis.

— A

small Lachesis with_singlesubcaudals, 17 rows_{of scales,} and an_enlarged^fronta1shield.

Range.

—

_{Omilteme,Guerrero,} Mexico.

Type.

—

UnitedStates National

Museum,

^No.46,347. Omilteme, Guer- rero, Mexico.

Descriptionoftypespecimen.

—

Scales in17 rows, the^firstsmooth,^therest keeled. Ventrals 154, anal _entire, subcaudals 32 _{(23 single,} followed

by

three paired^shieldsfollowed again

by

^sixsingleones)^. Tail apparentlynot prehensile. Supraocularslarge,separated ^acrossthehead

by

^threeshields

ofwhich^themedianisalarge frontal

and

thelateralonesform_partofa

row

separating^frontalfrom supraocular. Supralabialseightleft, nine_right

—

noneenteringpit. Infralabials nine,three touching theonepair of geneials.

Two

preoculars, four suboculars, twoofwhich touch^thethird andfourth labialsandthelasttwoofwhichare separated

by

^{onescalefromthelabials}

—

threepostoculars. There are from oneto three keels onthe temporal scales. Nasal divided

—

one scale between preocular

and

nasal, a _large scale in front ofsupraocularon_topofsnout. Canthusrostraliswhiledis- tinctdoes notformanacuteridge as inL. godmani.

Uniform dulloliveabove.

On

the_posteriorfifthofthe

body

^thereare

indistinct lightspotsontheendsofthe ventrals

and

on

some

ofthescales

44—

Pboc.Biol. Soc.Wash., Vol.32,1919. (213)

214 Proceedings

of theBiological Society of

Washington.

ofthefirstthree rows. Thesetake theformof lightbars fourorfivedorsal scalelengthsapart.

The

scalewhichhas thelightspot^alsohas adark_tip.

On

^thetailthesenarrow crossbarsextendtothemid-dorsalline. There arefoursuchlightbarsonthe_tail,theposterior third ofwhichisuniform anddarkerthanthecolorelsewhere.

The

_bellyisveryfinelypunctulated withlightanddark.

Head

above

same

asbody, anindistinct light

band

from_eyetoangleofjawincluding the^lastfourupper^labialsand_extending

more

orless continuouslythoughfaintly above _{the edges}of the ventrals throughthe anteriorhalf ofthebody. Throat dark,^lastsixlowerlabials withaverticalwhitebar.

Dimensions.

—

_Length,370

mm.

;tail,46

mm.

Remarks.

—

Thissnakemeritscomparison with^L.godmani

and

L._aurifer ratherthan with

any

Lachesis hithertorecordedfromMexico (i.e., lanceo- latus,nummifer,lansbergii,brachystoma

and

undulatus)^{. It}has a lowerscale count than any Americanspecies.

With

aurifer (thenext_lowest,with 19scalerows)^{it isallied}

by

^{the en-} larged^frontalandthe ventral count.

But

itdiffersinthe smaller

number

ofsubcaudals,ⁱⁿ the

two

lessscalerows,ⁱⁿthe greater

number

of oculars,

and

ⁱⁿ

some

_beingincontactwiththe_labials,inthedividednasal, inthe labialsbeing occludedfromthe_pit,andin coloration.

With

_godmanithereiscloseagreement^{incolorationsavein}the peculiar throatofthe

new

form, thesubcaudalcountisthesame.

Godmani

some- times has the enlarged ^frontal separated

by

^one

row

of scales fromthe supraocular, the^labialsdo notenterthe_pit,andthe nasalisdivided.

But

here theresemblance endsforgodmani^{has 21scalerows, a}

much

lowerven- tral count, a

more

acute canthus rostralis

and

the suboculars are cut off

from the labials.

Itwould seemthat barbouriisalinkbetween godmani andaurifershowing charactersofbothand_being

more

_primitivethaneither in headscalation

and

having(dwarfingdueto altitude?)a lower

number

ofdorsalscalerows than either.

Itisinteresting tonote thatgodmani andaurifer areusuallyput^indiffer- entsections ofthegenus ^becauseofthe possession ^ofa prehensile^tail

by

aurifer,

and

these sections have been ^elevated at times to generic rank.

BothriechisPeters _1859, type ^B.nigroviridis Peters, for the_{arboreal, pre-} hensile tailedforms;

and

Bothriopsis Peters 1861, type B. quadriscutatus Peters (=castelnaudi

D &B

^fideBoulengeretCope),^fortheterrestrial,non- prehensile^tailedforms.

Idonotbelievethat thesedivisionscan be maintained onthischaracter.

Bothriechis is thereforethe _generic

name

for the American Lachesiswith undividedsubcaudalsincasethey^arethoughtnot congenericwithL.mutus

and

L.atrox.

Crotalus stejnegeri, sp. nov.

Diagnosis.

— A

small Crotaluswitha long slendertail,avery^smallrattle

and

withthefirstpair oflowerlabialslong

and

produced backwards broadly incontactbehindthe symphysial.

Dunn — Two New

Crotaline

Snakes from Western Mexico. 215

Range.

— West

coastofMexicoinSinaloaandwesternDurango.

Type.

—

UnitedStatesNational

Museum,

^No.46,486. Plumosas,Sinaloa, Mexico;July 19,1897. Nelsonand

Goldman

collectors.

Descriptionoftypespecimen.

—

Scales in27 rows, the^firstsmooth,^therest keeled. Ventrals 176, anal _entire, caudals 44 undivided. Rattle very small,seven_ringsand button measuring¹²

mm.

_longandfour

mm.

wide.

Upper

^{surfaceofsnoutwith one}largepair of internasals

and

arow^offour prefrontals,thetwooutsideonesincontactwithinternasalandsurpraocular

—

canthus rostralisdistinct. Supraocular ^shieldsnarrowerthan_{space be-} tween them, smooth

—

7-9scalesbetweensupraoculars,and 10-13scalesin contact with them.

Two

^scales betweeneye and nasal.

Eye

separated fromlabials

by

^{threeseriesofscales. Rostralincontactwithnasal.} Supra- labials 14 _L, 15 R; ^{lower labials} 16, the first pair produced backwards incontactwith eachotherbehindthesymphysial and with^thethirdlower labial, thus cutting the second lowerlabial fromthe chin shields. Color grayish-brown; a^{series of}40darkerbrown,black-edged^dorsal

rhombs

(the firstofwhich^issplitonthe neck) three^scaleslong

and

onsevenscalerows.

Alternatingwiththeseon^theninthscale

row

a darkspot covering about onescale. In the

same

transverse plane^asthedorsal

rhombs

dark_spots coveringabout onescale ineachofthe_third,fourth

and

fifthrows. Alter- natingwiththeseadark_spotonascale ofthefirst

row and

the_{tip of} the precedinggastrostege. Belly grayishmarbled withblack. Tail dull

brown

withindistinctdarkcross-bands.

Head

fleckedabove withblack,adarker

brown

blackedged

band

from beneath_eyetoangle^ofjaw.

Lower

half of upper^{labialswhite.} Throatwhite,adark_spotbelow_angleofjaw andtip oflowerjawgrayish.

Variation.

— A

smallerspecimen with^arattle consisting ofbuttonalone

—

UnitedStates National

Museum,

^No. 46,460, with the

same

_data,shows few minorvariations.

On

onesidefourseriesof scales separateeyefrom

labials.

The

second lowerlabialisnarrowlyⁱⁿcontactwiththe chinshield, thus separating the^{first labial} from the third.

The

scale countsfor this specimen ^are

V

174,

C

41, Sc _27,

L

_14/13-14.

Same

_patternas type.

Forty-four^dorsalrhombs, twoelongated black spotsonocciput,adark_spot which^ispartly onthe_posteriorend of the supraocular

and

asimilarspot partlyontheanteriorendofthe

same

scale.

Dimensions.

— _Type

No. 46,486. Total _length, 590

mm.;

^tail except rattle77

mm.

No.46,460, total length,284

mm.,

^tailexceptrattle,33

mm.

Remarks.

—

This snake _scarcely needs comparison with any ^described form.

The

subcaudals are

more

in

number

than in

any

^of the described species.

The

shape^ofthetailandtheminutenessoftherattlearecharac- terswhich_scarcelystandouton paper but which^are verystriking inthe specimens.

The

peculiar shape ^{of the first lower labial is} unique, ^also.

In _pattern stejnegeri is remotely ^{similar to} the snakes of the triseriatus- priceigroup,but evenhere therelationship^isnotclose.

Boulenger (Cat. SnakesBritish

Museum

III, p. 580) records aspecimen of C._tigris fromVentanas, Durango, Mexico, onthewestern_slope ofthe Sierra

Madre

about 15milesfromthe Sinaloaborder

and

undoubtedlyⁱⁿ

216 Proceedings

of^theBiologicalSociety of

Washington.

the

same

faunal zoneasPlumosas. Thissnake

was

Boulenger's onlyspeci-

men

oftigris. It

was

small (380

mm.) and

has the following^scale count:

V

181,

C

46,Sc25. Istronglysuspect that^{it is}the presentspecies.

The

caudal countis far too high^for tigris. Unfortunately^{it is} impossible to determine

how much

ofthe descriptionⁱⁿtheCatalogue^ofSnakesis

drawn

fromthisspecimen and

how much

fromliterature. Stillacomparison with the descriptionabove shows

many

points ^ofresemblance

and

afewof dis- cord otherthanthetwolessscalerowsandtheslightventral

and

caudalvari- ations. Also the following statements are notinaccordwith thestate of affairsintigris. "Snout withdistinctcanthus,""alarge scaleon eachside betweentheinternasal

and

the supraocular," "three^{seriesofscales}between the eyesandthelabials,""dark-edgedspots."