CHAP. XIX.] 
REPTILES. 
385 
the Nearctic is actually richer than the Neotropical region both 
in genera and species. This would point to the conclusion, that 
the group originated in the Indo-Chinese sub-region and spread 
thence north-east to North America, and so onward to South 
America, which, having been the last to receive the group, has not 
had time to develop it largely, notwithstanding its extreme 
adaptability to Reptilian life. The genera are divided among 
the several regions as follows : — - 
Craspedocephalus (7 sp.), Tropical America and the West In- 
dian Islands; Genchris, Crotalophorus , TJropsophorus, and Crotalus, 
inhabiting North America from Canada and British Columbia 
to Texas, one species ( Crotalus horridus) extending into South 
America; Trimeresurus (16 sp.), all India from Ceylon to Assam, 
Formosa, the Philippines and Celebes; Peltopelor and Hypnah 
(1 sp. each), peculiar to India ; Calloselasma (1 sp.), Siam ; 
Atropos (1 sp.), Java and Borneo; Halys (3 sp.), peculiar to 
Tartary, Thibet, Japan, North China, and Formosa. 
Family 25. — VIPEKID2E. (3 Genera, 22 Species.) 
General Distribution. 
Neotropical 
JSUB-SEaiONH. 
Ne ARCTIC 
Sub- regions. 
Pal^: arctic 
Sub- regions. 
Ethiopian 
Sub-regions. 
Oriental 
Sub-regions. 
Australian 
Sub-reg IONS* 
1 . 2.3 .4 
1 . 2 . 3 . 4 
J 
1 . 2 . 3.4 
1 
The Viperidm, or True Vipers, are especially characteristic of 
the Palsearctic and Ethiopian regions, only one species being 
found over a large part of the Oriental region, and another 
reaching Central India. They are especially abundant in Africa, 
and the Palsearctic confines in South-western Asia. The 
common Viper ranges across the whole Palsearctic region from 
Portugal to Sagh alien Island, reaching to 67° North Latitude, in 
Scandinavia, and to 08 in Central Siberia. The genera, accord- 
ing to Dr. Strauch’s synopsis, are distributed as follows 
Vipera (17 sp.), which has the range of the family, extending 
over the whole of the Pahearctic and Ethiopian regions, except 
Madagascar, and as far as Ceylon, Siam, and Java, in the Oriental 
VOL. II. 
c c 
