38 2 



may be brought as properly as marine birds into the statement of the 

 ratio between the number of species and the area of dry land . A second 

 form, quite peculiar to this region, are Snakes covered with granular 

 tubercles, Chersydrvs, Acrochordus, Xenodermus ; without being ve- 

 nomous, they approach to the Hydridee by the genus Chersydrus, an 

 inhabitant of rivers and their mouths, and with an organization like 

 that of true Sea-snakes. As the family of the Lycodontidce is to be 

 assigned to the Indian and African region, each exhibiting different 

 genera, so that of the Cahtmaridce is divided in the same way between 

 the neotropical and this region ; whereas Homalosoma and two species 

 of Rhinostoma perhaps afterwards may be separated from this family. 

 The above-mentioned genera of Calamaridce are very characteristic, 

 and the very aberrant forms which abound in India are here repre- 

 sented by a genus of this family having no palatine teeth. Those 

 intermediate forms between the well-proportioned structure of the 

 familv of Colubridee and the excessively slender one of the true Tree- 

 snakes, which I unite in one family of Dryadidce, and which are so 

 common in the Neotropical region, are scarcely represented by some 

 species of Cyclophis and Gonyosoma. The genus Aheetulla is here 

 represented by Hendrophis — in one species (D. pieta) extending to 

 New Guinea, in another (D. punctulata) to Australia. Dryophis is 

 found in the Neotropical region as well as in the Indian one, but 

 the species of both regions differ in dentition ; the African species 

 (D.Kirtlandii) agrees with the South x\merican ones ; finally, Pas- 

 serita is only limited between the boundaries of the East Indies. If 

 we exclude the Hydridee, the number of venomous Colubrince is 

 far surpassed by that of the Viperina, and all the latter exhibit the 

 peculiarity of having a pit on the side of the face, which is also found 

 in the representatives of the New World, not in those of Africa. 

 Ceylon offers a remarkable exception, producing a form without such 

 a pit. 



Among those large islands which are connected with the Middle 

 Palseotropical region, none offer forms so different from those of 

 the continent and the other islands as Ceylon : it might be considered 

 the Madagascar of the Indian region. We not only find there pecu- 

 liar genera and species, not again to be recognized in other parts, 

 but even many of the common species exhibit such remarkable va- 

 rieties, as to afford ample means for creating new nominal species. 



1. Calamaria and Elaps are not represented in this island. 



2. The following species are common to Ceylon and the other 

 parts of the region, the Ceylonese specimens exhibiting no remark- 

 able variation : — Simotes russellii, Coryphod. blumenbachii, Ablabes 

 collaris, Chrysopelea ornata, Dendrophis picta, Tropidonot . stolatus, 

 Lycodon mdicus, Naja tripudians. 



3. Ceylonese specimens of the following species always exhibit 

 one and the same variation : — Simotes purpurascens, Tropidonotus 



Panama, and were about the size of an eel. I have not the slightest reason to 

 doubt the credibility of the observers ; but as long as we have not obtained them, 

 it will always be a question whether the animals seen are Snakes or not. 



