Poijonouj Snakei of f/»e World 



VfiiKUi U .stronyly to\lr. iniislnt: \vlilrs|in'iul llssiir ilc 

 slnu'tloii anil hIt'rtlhiK fi"m iiiucoiis mcinliniiics. IimiIi 

 fvlfnuill.v aiul liitcrimll.v. A puff lulilcr of iivrnii;!' di 

 im-lisliilis limy lllivi> slltllril'llt vciicnii In kill I In .'i llicll. 

 Dfiitli limy iii'l 'iri'iir fm- iimrc limn 2^ hours and Is 

 usually prfii'«lftl by si-vcrc inlcnml licniniorliimcs. Tlu' 

 snake Is nui'liirnal, slow iiiovIiik. anil li'iiils In ii'iiiiiiii 

 liniiiohilt" when aiiiiroarlnMl, 



Aniivi-nins aii- inoilurt'il liv r.rliilM;;ui'rki', llir Instil ill 

 I'astfiir. iiiiil lln- Smilli Afiiran Insliliili- for MimIIimI 

 IJi'st'iinli. 



River Jack, /lifis naslcorii/-^ (Sliaw). 



hh iitifiiiiliitii: \ lai-Ki' anil cxlri'iiii'ly thlcU-liodlofl 



viper with relatively small head and Iw ■ llini' 



pairs of nasal ••horns." Most easily distinguished froni 

 the Cabooii viper ( wliiili may have a pair of nasal 

 ■liorns'i l>y the lar^-e dark arrow-shaped mark on .the 

 crown. Adult snakes are l^'j to ."iVj feet in length; ex- 

 eeptionnl individuals attain a leiiKth n( I feet. 



Hody pattern very eoniplex. usually made up of a 

 vertebral series of 1.")-1S [laired. vellow-edKed blue 

 blotihes. with a lateral series of li>;ht-edf;ed dark tri- 

 anules exteiidinj; up from the belly, (iroiiml color varies 

 tbroii-h various shades of blue. pink, purple, and green. 

 In spite of its brilliant colors the pattern blends well 

 with the forest tlnor. 



Dorsals in 3."j— 11 rows at niidbody. ^'entrals 1"J4- 

 140; subeaudals 10-32. 





Figure 72. — River .Tack. Ilitin iiiiairdniin. The arrow- 

 shaped head marking is distinctive. Photo by Isabelle 

 Hunt Conaiit. (See also [ilate II, figure 3.) 



Disirihiitioii: Swamps, river banks, and other moist 

 habitats through the tro|iical rain forest region from 

 Liberia and Uganda s<juth\vard through the Congo re- 

 gion. 



Remarks: The river jack has a more restricted 

 range than the gabooii viper and apiiarently inflicts 

 even fewer bites. However, its venom is reported to 

 be highly toxic and it is not as placid as the latter. 



Antivenins are produced by Behringwerke. the Institut 

 I'asteur. and the South .\fricaii Institute for Medical 

 Re.search. 



VIPERIDAE: Genus Cousus Wciglcr, 1830. 

 .\l;^lil aililers. 



Koiir species are found III tropical and southern Africa. 

 .None attains a length of over .'1 fed. The fangs are 

 relatively small, and the venom is rather mildly toxic. 

 They look surprising like noniioisonons snakes. .N'ight 

 adders are iml con^idcic'd (langcrniis to life but Ibcir 

 bile is painful. 



Dcfiiiil iiiii : Ilc.iil iNoilcratc in si'/.e, fairly distinct 

 from neck, an olilusc canlhiis. l'.<Mly cyliiHliiciil or 

 slightly depressed, moderately slciiilcr : tail short. 



l':yes moderate in size: pupils round. 



Head scales: The usual crown scales; rostral 

 broad, sometimes pointed and uplnrned; frontal long, 

 supraoculars large. I,aterally, a loreal present, sejiarat- 

 ing nasal and preoculars; suboculars present, separating 

 eye from labials. 



Hody scales: Dorsals sn th or weakly keeled, with 



apiial pits, in l."-^22 obli<|ue rows at midbody, fewer 

 111 111 posteriorly. Wntrals rounded, lOO-l")."! ; sub- 

 caiidals single or |iaircd, 10-33. 



Rhotnbic Night Adder, Criusus rhonihrafiis (Lioh- 

 Iciisleili). 



Idcntificutiini: A satiny sheen to the .scale.s and a 

 V-shaiied marking on the back of the head are character- 

 istic of Ibis snake. It differs fr<jni llie other night ad- 

 ders in having a rounded snout and a relatively lui- 

 inoditied rostral scute. Adults average about 2 feet in 

 length ; exceiitional individuals reach "close on 3 feet." 



Ground color light gray to dark brown or olive with a 

 series of 20-30 squarish blotches down the back ; irregu- 

 lar markings laterally. Markings are often white-edged. 

 I'nicolor white or yellowish below, ventrals occasionally 

 have dark edges. 



Distrihution: Widely distributed through the savan- 



Fic.tRK 73.— Head scales of Rhcmlbic Night Adder, Vau- 

 6-H.s' rhoiiihcatiis. Note the rear projection of the 

 rostral, the presence of a loreal, and of suboculars; 

 all of these are characteristic of the genus. (See 

 also [ilate VIII, tigs. 4-0). Redrawn from ritmun, 

 1938. 



102 



