384 



IV. Australian or Eastern Pal&otropical Region (Regio 



Australiana.) 



Characteristic forms. — Morelia, Liasis, Nardoa, Enygrus, Bo- 

 lyeria, Myron, Glyphodon, Diemansia, Hoplocephalus, Pseudechis, 

 Pseudonaja, Br achy soma, Vermicella, Acanthophis. 



Forms common with other regions. — Cerberus, Dendrophis, Dipsas, 

 Hydrides. 



What I have said in the beginning of my notices on the iEthio- 

 pian region I can as justly repeat respecting this part of the globe, 

 the borders only of which are known to us ; so that the propor- 

 tionate numbers here given will be far from truth, and can be only 

 considered to be proportionate to our present knowledge. If we allow 

 50 species as peculiar to this region, and take the area of dry land at 

 3,000,000 square miles, we have on the average a single species to 

 each 60,000 square miles, or 2^- species for the same area in the 

 vEthiopian ; but the Indian region is richer, giving 3£ species for the 

 same area, in which we have only one in the Australian. 



We find a peculiar character of this region in the ratio between 

 the numbers of species in the different sections of the Snakes. Two- 

 thirds are venomous snakes — a disproportion not again to be found 

 in any of the other regions, where the number of innocuous snakes 

 always far predominates ; secondly, two-thirds of the non-venom- 

 ous snakes are Boidce ; thirdly, there is only one genus (Acan- 

 thophis antarcticd) belonging to the tribe of Viperina, the whole 

 number of the other venomous snakes being constituted by Colu- 

 brina with grooved fangs. We know only six non-venomous Colu- 

 brina from New Holland, two of which (Coronella australis and 

 Tropidonotus picturatus) belong to cosmopolitan genera, the third 

 (Dipsas fused) to a tropicopolitan genus, the fourth and fifth (Den- 

 drophis punctulata and Cerberus australis) to East Indian ones ; for 

 the sixth (Myron Richardsonii) a separate genus was established, 

 but it is closely allied to the East Indian Hypsirhina. The genus 

 Elaps, represented by a different form, Vermicella, is so far from being 

 capable of being united with the East Indian forms, that it is nearer 

 to those of the Neotropical region. Thus if we except three species 

 and the Hydridce, which are subjected to quite other physical con- 

 ditions, we have in the Eastern Palaeotropical region a fauna of Ophi- 

 dians as widely different from the nearest one of the East Indies as 

 from all the other ones. It must be mentioned, that there is no snake 

 known for the present from New Zealand. I say, for the present ; 

 for not many years since a total absence of Serpents in all the nume- 

 rous isles of the Pacific Ocean was believed in. 



V. Nearctic or North American Region (Regio Nearctica). 



Characteristic forms. — Charina, Wenona, Conopsis, Conocephalus, 

 Carphophis, Osceola, Ninia, Lodia, Sonora, Rhinochilvs, Tan til la, 

 Simotes ? coccineus, Ischnognathus, Helicops, Farancia, Dimudes, 



