Pouonout Snakes o^ iho World 



Stall's ami iioillirni Mi'\ini; oiii" spcclt'S If. iliirininin) 

 raiitfcH .toiilliHaril liilo .siiiithi-rn Simtli Aiiu-rlia, Iwo iirr 

 fiimid rast i>r IIh" Mississippi ItlvtT, and Iwii as I'm- 

 ninth as Caiiatla. A (vw nf llii- very small spcrli-s and 

 small liullvldiials nf lurKi' spt'cleii (Ions tliati L' ft-t't ) may 

 iiffiT lltlli' daiiKt'i'. t'lil most sptM'Ics dn; some arc Id^ldy 

 daiiKt-roiis. 



Hiflnitiiiii: Head brnad, very distinct ffom narriiw 

 neck; i-anlliiis dlsllnit to absi-nt. Hudy cylindrical, de- 

 pressed, or sIlKldly I'omprcsscd. inddiMalcly slender Id 

 stout ; tall short with a horny scKmeiilcd rattle. 



Eyes small; pupils vertiially elliptlial. 



Head scales: Supraoculars present, n \tn\v of inlcr- 

 na.sals often dlsttiict, occasionally a pair nf pnfrontals : 

 eidnr;;ed canthal scales often present ; other parts of 

 crown covered with small scales. Laterally, eye sepa- 

 rated from siipralahials by !-."> rows of small scales. 



Hody scales: Dorsals keeled, with apical jiits. in 'lO- 

 ;{.'{ noiiobliipic rows at inidbody. Ventrals 132-^200; suh- 

 cainlals 1.'5- l."i. all siiijile or with some terminal ones 

 paired. 



Cascabel, Civfii/ns dur'lssun Liiiiiiieus. 



Iihiili/iratioii: The only true rattlesnake in most of 

 its raiifie I except in .Mexico). The series of large rhom- 

 bic blotches (diamonds) down the back, stripes on the 

 neck, and the large rattle are distinctive. Body stout 

 and slightly compressed, especially anteriorly. Adults 

 average 4 to ."> feel ; maximum length about (! feet. 



Body brown or olive with ],S-.S."i darker, light-edged 

 rhomb-shaped markings down the back. Those on neck 

 sometimes elongate into stripes. Tail usuall.v unicolor 

 dark brown or black. White or cream colored below. 



FiGtTRE 43. — Cascabel. Crotahis flidisfiiis. Photo cour- 

 tesy Scimtiflc Antoicaii. (See also jilate I. fig. 3.) 



Dintribution: Dry areas, grasslands, and thorny 

 scrub, from coastal eastern and southern Mexico south- 

 ward through Central America, and through eastern 

 South America from northern Colombia to northern 

 Argentina. 



Ii'iiiiiirl.s: This Is one of the most dangeronM of the 

 ralllesiiakes, and Is one of the most dangeroUK snakes 

 III llie Americas. The loxlilly of the venom varies 

 lliroiigh I he range: In llra/,11. where the cascabel is 

 the main cause of ilcalli from snakebite, It Is extremely 

 toxic. The venom of ihls rattlesnake has minor local 

 elTecl bill very grave systemic syiiiptoms. These in- 

 clude blindness, paralysis of the neck miis<'les, cessa- 

 tion of brcalliing and heartbeat, and llnally death. 



This venom does not appear to form adeipiate anti- 

 bndics in horses, so that enornunis amounts of ariti- 

 vcniii are needed to counteract the effects of llic bile 

 of a siiiiUc of average dimensions. Ten ampules (100 

 ml. I would appc.ir In be an average initial dose, and 

 20 or more may be used. 



.Vnlivenins ar<' produced by llic Insliliilo Itutantan and 

 liistilulo l'iiilicir<is. liiazil, and Wyclh, Inc., I'hila- 

 dclphia. 



Aruba Rattlesnake, Cfo/nhis iinicoh/r Lidfli de 

 .feiide. 



liliiili/icdtiijii : \ gray or gray-brown rattlesnake 

 which is unicolor, (jr wilh a faint pattern of rhomb- 



FiGUUE 44. — Aruba Rattlesnake, ('rottilns uiiicohir. This 

 faded relative of the cascabel occurs only on the 

 island of Aruba. Photo by New York Zoological 



Society. 



shaped blotches (diamonds) down the back; the only 

 venomous snake on Aruba Island. Body stout and 

 somewhat depressed. Adults average 2 to 3 feet ; maxi- 

 mum length a little less than 3S inches (O.'iO mm.; Klau- 

 ber, 19.j6), 



Body gray or light gray-brown with lS-28 faintly 

 darker rhomb-shaped blotches down the back; blotches 

 sometimes almost indistinguishable. A lateral series 

 of ob.solete blotches that alternate with or oppose the 

 dorsal series. I'sually a distinct pair of parallel stripes 

 on the rear part of the head ; these may continue as 

 stripes on the neck. White or cream-colored below. 



Dorsals strongly keeled, in 25-27 rows at midbody, 



68 



