CHAP. XIX,] REPTILES. 387 



lidae. The Australian has 16, belonging to three families only ; 

 eleven being Elapidae, and four Pythonidse. The Neotropical has 

 about 24, belonging to eight families ; ten are Colubridse, six 

 Pythonidae, and the rest Dipsadidae, Scytalidae, Amblycephalidae, 

 Elapidae, and Crotalidae. 



We find then, that in the Ophidia, the regions adopted in this 

 work are remarkably distinct ; and that, in the case of the Orien- 

 tal and Ethiopian, the difference is strongly marked, a very large 

 number of the genera being confined to each region. It is in- 

 teresting to observe, that in many cases the affinity seems to be 

 rather between the West Coast of Africa and the Oriental 

 region, than between the East Coast and the plains of India; 

 thus the Homalopsidae — a highly characteristic Oriental family — 

 occur on the West Coast of Africa only ; the Dryiophidae, which 

 range over the whole Oriental region, only occur in Madagascar 

 and West Africa in the Ethiopian ; the genus Dipsas is found over 

 all the Oriental region and again in West Africa. A cause for this 

 peculiarity has been suggested in our sketch of the past history 

 of the Ethiopian region, Vol. I. p. 288. In the Lycodontidae, 

 which are strictly confined to these two regions, the genera are 

 all distinct, and the same is the case with the more widely dis- 

 tributed Elapidae ; and although a few desert forms, such as 

 EcMs and the Erycidae, are common to Africa and the dry plains 

 of India, this is evidently due to favourable climatic conditions, 

 and cannot neutralise the striking differences in the great mass 

 of the family and generic forms which inhabit the two regions. 

 The imion of Madagascar with the South-western part of the 

 Oriental region under the appellation Lemuria, finds no support 

 in the distribution of Ophidia ; which, however, strikingly accords 

 with the views developed in the Third Part of this work, as to the 

 great importance and liigh antiquity of the Euro-Asiatic conti- 

 nent, as the chief land-centre from which the higher organisms 

 have spread over the globe. 



Fossil Ophidia. — The oldest known remains of Ophidia occur 

 in the Eocene formation in the Isle of Sheppey ; others are found 

 in the Miocene (Brown Coal) of Germany, and in some Tertiary 

 beds in the United States. Most of these appear to have been 



