Poisonous Snakoi of tho World 



otXvr III I If ilan;:rr. lull iiinst s|ii'i'l('s i|i>; siiiiii> iil't' IiIkIiI.V 

 ilaiiKi'ii'Us. SfVi-nil spfclcH i-atii;<> liiti> tills region (mc(> 

 p. .-.0). 



HvJIiiitiiiii : lli'iiil l>ii>ii(l. M'ly ili^lliicl ri'imi iiairnw 

 lUfk. i-ailtliiis (llstiiiit III iiliM'Ml. Itddy r.vlliKll'Irill, ili'- 

 prossiMl. i>r sliKlitly (•i'iii|in'ss»Ml, iiiudcralt'ly sIimkIit hi 

 stout; tail short with a tioniy scuini'iitcd raltlf. 



Kycs small; pupils vcrlli iiUy ("llipllciil. 



Head scales: Siipninriiliirs preseiil. ji pair of iiiler- 

 iiasals ofleii dlstiiu-t. oicasloiially a paii' of preriontals ; 

 eiilarjced raiitlial scales often present ; other parts of 

 iTowu covered with small scales. Laterally, eye sepa- 

 rated from siiprnlabials liy 1 ." rows of small scales. 



Hody scales: Dorsals keeled, with apical pits, in I'.i 

 ."V? noiiolilii|iie rows at midbody. Ventrals i;J2 2(Ki ; siili- 

 caudals i:? 4.'i, all single or with some termiiinl ones 

 paired. 



Mexican West-coast Rattlesnake, Crolnhis husiliscHs 



(Coin'). 



Iiloitipnition ■ The only rattlesnake within its range 

 with diamond-shaiied dorsal niarkiims. Body moder- 

 ately stout and rather triaiiKiilar in cross section. 

 Adults average 4 to ."> feet: niaxinium length 6 feet, 

 9 3/4 inches I Klauher, lir.tJ). 



Head uniform grayish brown or olive green except 

 for dark postorbital bar and lighter labials; no distinct 

 markings on crown or neck. Body brown or grayish 

 olive with 2G-41 dark light-edged, rhomb-shaped (dia- 

 mond) blotches. Tail gray, darker-banded or almost 

 uuicolor without distinct markings. White or cream- 

 <-olored below. 



Dorsals strongly keeled, in 25-29 rows at midbody, 

 fewer posteriorly. Ventrals 174-200 ; subcaudals 1.S-3G. 



DixtrihKtiiDi : The coastal i)lain and mountain slopes 

 of western Mexico from southern Sonora to central 

 Oaxaca. Mainly an inhabitant of thorn forest, but 

 ranges upward into tropical rain forest in the south. 



Rctiiaik.1 : Little has been renorted on the effect of 



J^S&S* 



the bite of this species. However, It produces large 

 iiiiioiints of a highly toxic venom. A large Individual 

 is iiiiqiiesl lonably a dangerous snake. 



I'olyvalciit antlvcniii Is produced by the Instltuto 

 .Nacional de Iligiene, .Mexico. 



CROTALIDAE: Genus Lochesis Daudin, 1803. 

 Hiisliiiiasli'i'. 



-V single species, h. iiiiiliix, is fmniil in li'iipiial .Vnier- 

 Ica. It attains a Iciiglli of !» to 12 led and is considered 

 dangerous. 



Di/iKitioii : Head broad, very ilistinci from narrow 

 neck ; snout broadly I'ouiided, no caiithus. Body cylin- 

 drical, tapered, moderately stout; tail short. 



Eyes small : pupils vertically ellijitical. 



Head s<ales: A pair of small inlernasals separated 

 from one another by small scales; a pair of narrow 

 supraoculars; other parts of crown covered with very 

 small scales. I,aterally, second supralabial forms an- 

 terior border of loreal pit, third very large; eye sepa- 

 rated from supralabials by 4-.") rows of small scales. 



^SfSS 



Figure 31. — Mexican West-coast Rattlesnake, Crotahis 

 hasilisciin. Photo by San Diego Zoo. 



Figure 32. — Inderside of Tail Tips of a Lancehead 

 (Bothrops), above, and the Bushmaster {Lachesis), 

 below. The spiny "burr" formed of divided sub- 

 caudals is distinctive of the bushmaster. Drawings 

 by Lloyd Sandford. 



Body scales; Dorsals heavily keeled with bulbous 

 tubercles, feebly imbricate, in 31-37 nonoblique rows 

 at midbod.y, fewer posteriorly. Venti'als 200-2.30; sub- 

 caudals mainly paired, 32-50, followed by 13-17 rows of 

 small spines and a terminal spine. 



Bushmaster, Lachesis m%(ti(S (Linnaeus), 

 Identification: This large tan or brown snake with 

 black or dark brown rhombs is easily recognized. The 

 peculiar burr of pointed spines near the end of the 

 tail is distinctive. Adults average 5 to 7 feet In length ; 

 occasional individuals attain a length of 9 feet ; a maxi- 

 mum of 12 feet has been reported. 



Ground color tan or pinkish with 23-37 black or 

 brown rhombs on body. Markings with light centers ; 

 tail dark with light crossbands. A dark postorbital 



56 



