Southeast Asia 



serious bite indicate that it is a dangerous snalie with 

 venom similar to tliat of Ecliis (see p. 110, fig. 75). 



Definition: Head broad and flattenetl, very distinct 

 from neck ; snout broad and short, canthus not distinct. 

 Body slightly depressed, moderately to markedly stout ; 

 tail short. 



Eyes moderate in size; pupils vertically elliptical. 



Head scales : Crown covered by small scales ; rostral 

 broad, bordered dorsally and laterally by greatly en- 

 larged nasorostral scales. Laterally, eye separated from 

 labials by .'5—1 rows of small scales ; nasal separated from 

 rostral by nasorostral scale. 



Body scales : Dorsals keeled, short, in 2.3-26 vertical 

 rows at midbody. Ventrals with lateral keels, 140-148 ; 

 subcaudals paired, without keels, 29-36. 



VIPERIDAE: Genus Pseudocerastes Boulenger, 1896. 

 Fixlse-lionu'd vipei'. 



A single species is recognized (see Remarks, pp. 110- 

 111). It ranges from Sin.-ii .-uid the Arabian Peninsula 

 eastward to West Pakistan. It attains a length of 3 

 feet and is considered dangerous. 



Definition: Head broad, very distinct from neck; 

 snout short and broadly rounded; nostrils dorsolateral, 

 valves present. 



Eyes small to moderate ; pupils vertically elliptical. 



Head scales : Crown covered with small imbricate 

 scales; an erect hornlike projection covered with imbri- 

 cate scales above eye. Jjaterally, nasals sejiaralcd from 

 rostral by small scales ; eye separated from labials by 

 3^ rows of small scales. 



Body scales : Dorsals weakly to moderately keeled, 

 in 21-25 nonoblique rows at midbody. Ventrals 134- 

 158 ; subcavulals paired. 35-48. 



VIPERIDAE: Genus Vipera Laurenti, 1768. 

 True addei's. 



Eleven species are recognized. This is an especially 

 variable group, with some members that are small and 

 relativel.v innocuous (e.g., 1'. Ix-riim and others that are 

 extremely dangerous (I", lebetina, 1'. nixsrlii). They 

 are found from northern Eurasia throughout that con- 

 tinent and into north Africa. One species ranges into 

 the East Indies ( 1'. niiiselii) , and two are found in 

 east Africa (see Remarks under T'. stiperciliaris). Rus- 

 sell's viper and the Levantine viper (p. Ill) are the 

 (inly nu'iuliers of this genus in the region. 



Definition : Head broad, distinct from narrow neck: 

 canthus distinct. Body cylindrical, varying from mod- 

 erately slender to stout : tail short. 



Eyes moderate in size to small : pupils vertically el- 

 liptical. 



Head s<-ales : Variable: one species ( T. nrsinii) lias 

 all !> crown scutes, most species have at least the supra- 

 oculars, but even these are absent in one ( 1". Irhelina ) : 

 head otherwise covered with small scales. Laterall.v. 

 na.sal in contact with rostral or separated by a single 



enlarged scale (the nasorostral). eye separated from 

 sui)ralabials b.v 1— I rows of small scales. 



Body scales : Dorsals keeled, with apical pits, in 

 Ht-31 nonobliipie rows at midbody. Ventrals rounded. 

 120-180: subcaudals paired. 20-64. 



Russell's Viper, ]'/j/eni iiisneln (Shaw). 



Iilentifieution: Head wide, rather long; no enlarged 

 plates on crown ; no loreal pit ; scales keeled. These 

 features and the bold distinctive pattern readily dis- 

 tinguish this rei)tile from most other Asian snakes. 

 It may be closely imitated by the harmless Russell's sand 

 boa iEnjx conieim). however this species has narrow 

 ventrals (less tlian the width of the belly) and a very 

 short tail. 



Color deeii yellow, tan, or light brown with 3 rows of 

 large oval dark black-ringed spots which may be nar- 

 rowly edged with white; the spots of the middle row 

 often fuse on the latter half of the body; light V or X 

 .shaped mark on top of the head ; belly pinkish brown 

 to white with black spots. 



Populations of Ibis viper from Indonesia, Taiwan, 

 China and Thailand are more grayish or olive; there are 

 small sixits between the rows of large spots and the 

 belly is suffused with gray jxisteriorly. 



Average length 40 to ."lO iiuhes ; maximum 05 inches; 

 males larger than females. The island races average 

 smaller. 



Fkuuk <s!>. — Russell's Viper, Vipera riisselii. The oval 

 black-bordered markings are typical. Photo by R. 

 Van Xostrand. (See also iilate VI. figure 3.) 



Di.striliiition: Eastern West Pakistan, most of India. 

 Burma, and Ceylon ; parts of Thailand, southeast China, 

 Taiwan, and a few islands of Indonesia. Over most of 

 its range, a snake of ojien gra.ssy or brushy country often 

 common around cultivated fields and villages. Occurs 

 in lowlands, but avoids permanently marshy areas. Pri- 

 marily a hill or mountain snake in some places and has 

 lieen recorded at 7000 feet elevation. 



Remarks: Mainly nocturnal but occasionally active 

 by day in cool weather. Crawls slowly and is rather 

 phlegmatic in disposition. Hisses loudl.v when disturbed 

 and strikes with great force and speed. 



127 



