G LOG RAPII ICAL ZOOLOG Y. 
[part iv; 
38G 
region; Echis (2 sp.), inhabiting North Africa to Persia and 
to Continental India ; and Atheris (3 sp.), confined to West 
Africa. 
Remarks on the General Distribution of Ophidia. 
The Ophidia, being preeminently a Tropical order — rapidly 
diminishing in numbers as we go north in the Temperate Zone, 
and wholly ceasing long before we reach the Arctic Circle — we 
cannot expect the two Northern regions to exhibit any great 
variety or peculiarity. Yet in their warmer portions they are 
tolerably rich; for, of the 25 families of snakes, 6 are found in the 
Nearctic region, 10 in the Palmare tic, 13 in the Australian, 16 
in the Neotropical, 17 in the Ethiopian, and no less than 22 in 
the Oriental, which last is thus seen to be by far the richest of 
the great regions in the variety of its forms of Ophidian life. 
The only regions that possess altogether peculiar families of this 
order, are the Ethiopian (3), and the Oriental (2) ; the usually 
rich and peculiar Neotropical region not possessing exclusively, 
any family of snakes ; and what is still more remarkable, the 
Neotropical and Australian regions together, do not possess a 
family peculiar to them. Every family inhabiting these two 
regions is found also in the Oriental; and this fact, taken in con- 
nection with the superior richness of the latter region both in 
families and genera, would indicate that the Ophidia had their 
origin in the northern hemisphere of the Old World (the ancient 
Palmare tic region) whence they spread on all sides, in successive 
waves of migration, to the other regions. The distribution of the 
genera peculiar to, or highly characteristic of, the several regions 
is as follows : — 
The Nearctic possesses 9 ; four of these belong to the Colubridm, 
one to the Pythonidm, and four to the Crotalidm. The Palmarctic 
region has only 2 peculiar genera, belonging to the Colubridm, 
and Crotalidm. The Ethiopian has 25, belonging to 11 families ; 
four to Colubridm, five to Lycodontidm, and three to Elapidm. 
The Oriental has no less than 50, belonging to 15 families ; five 
are Colubridse, five Uropeltidm, twelve Homalopsidm, six Lyco- 
d on tube, three Amblycephalidm, eight Elapidm, and four Crota- 
