Dr. A. Giinther on the Geographical Distribution of Reptiles. 235 



One Viperine Snake with a rattle, Crotalus honndus, ranges into 

 this region ; but being also found in the more northern parts, and 

 having other relations in North America, it must be reckoned 

 among those of the latter region. 



Of the forms common to other regions there are found — 



1. In the ^'Ethiopian region, species o( Rhinostoma, Philodryas, 

 Ahcetulla, Drtjophis, Leptodeira, Bipsadoboa. In fact all the 

 species belonging to these genera show severally, according to each 

 different region, such different characters as may be hereafter con- 

 sidered to be generic, if they are again to be found in other species 

 of the same region ; and I wish therefore to point out a much greater 

 difference between both regions than might appear by the number 

 of forms mentioned as common. For instance, tlie South iVmtiican 

 species oi Rhinostoma exhibit a posterior grooved tooth ; in Rli'tno- 

 stoma cupreum of Africa I found the same tooth not grooved ; if Rh. 

 occipitale of Hallo well, from Western Africa, or other species hereafter 

 to be discovered, should prove to have also smooth teeth, I should 

 consider it to be a character sufficient to separate tlie Neotropical 

 species from those of the western Palteotropical region. Not know- 

 ing the species of Philodryas from Madagascar, I refrain from giving 

 my opinion in respect to them. 



2. In the Indian region, species of Rhabdosoma, Tomodon, Spi' 

 lotes, Coryphodon, Dryojihis, Eudipsas, Dipsadomorphus. I have 

 already pointed out that South Aiuerica exhibits in more than 

 one respect similarities with the middle Palseotropical region ; and 

 thus, excepting those forms which are represented in both regions 

 by different genera, we have two genera truly common to them, 

 Ithabdosoma and Coryphodon. The other genera I reckon of the 

 same account as those mentioned as common to the ^Ethiopian 

 region. 



3. In the Palseotropical region, one species oiTachymenis. 



4. In the Nearctic region, species of Heterodon, Herpetodryas, 

 Coryphodon. The first two genera are limited to the New World, — 

 one exhibiting more species in the northern part, the other more in 

 the south. 



The Ophidians decidedly show that the West Indies are referable 

 to the Neotropical region only. Hardly one species § is common to 

 them and to the Nearctic region, and only the genus Herpetodryas 

 might be considered such. Ou the other hand, many Southern con- 

 tinental species are again found in the West Indies ; and how many 

 generic forms are common to both, the number of genera marked 

 above vrith a cross (f) will represent. The genera peculiar to the 

 West Indies, and marked with an asterisk (*), do not express a 

 common peculiar character ; and some of them are founded on rela- 

 tively slight characters. 



§ Hallowell mentions Ischnognathu* Dekayi as found in Jamaica (Proc. Ac. 

 Nat. Sc. Philad. 1856, p. 237). 



