ON THE OEIGIN OF GENERA. 121 



examine to what extent the higher types exist in the Southern, 

 and lower or ancient in the Northern. 



The Percoid fishes and their allies have Australian and South 

 American representatives in their fresh waters, but they are as 

 mere outliers of the great mass in the Northern Hemisphere. The 

 higher tyj^e of venomous serpents (Solenoglypha) occur in both 

 the Ethiopian and Neotropical regions, but they preponderate in 

 the Northern Hemisphere. The higher group of the Saurians 

 (the Acrodonta) abounds in the Ethiopian and Australian regions ; 

 they are as abundant in the Indian and Palsearctic regions of the 

 Northern Hemisphere. In the Southern, also, by Uromastix and 

 the Eynchocephalia, they approach nearest the ancient types of the 

 Dicynodontia and the Crocodilia. Lacertidse, and not Teida3, 

 occur in the Ethiopian ; but they are but a proportion of the 

 whole, which chiefly exists in the Nearctic. 



Raniform, and not Arciferous Anura, populate South Africa ; 

 they, however, form but a small proportion compared with the 

 great series of the Nearctic, Palaarctic, and Palaeotropical regions. 

 It is, however, superior in Anura to the Nearctic, taken by itself. 



Easorial birds, and not Pullastrae, are the food sjiecies of South 

 Africa ; but they do not compare in abundance or size with those 

 of the three regions just mentioned. 



Moreover, but few Clamatores exist in either Australia or 

 Ethiopia. The Oscine types are abundant ; nevertheless, they can 

 not be compared in relative abundance with those of the northern 

 regions. It must also be remembered that the migratory capa- 

 bilities of birds render them less expressive of the true nature of 

 any fauna. 



The higher family of the Qnadrumana, the Simiidae, replaces 

 in Africa the Cebidae of the Neotropical ; they are, however, most 

 abundant in the Palaeotropical region, in the other hemisphere. 



There are two ancient or inferior types of the Northern Hemi- 

 sphere : First, its fishes, the Sturgeons of the Nearctic and Paloe- 

 arctic, and the Gars of the Nearctic* The latter only have rep- 

 resentatives in the Southern Hemisphere, Polypterus and Cala- 

 moichthys in Africa, and so may be said to be equally distributed ; 

 but the former are confined to the north. We do not know, how- 

 ever, whether they are of a modern or an ancient type, nor do we 



* Subsequent investigations have proved that Polypterus and Calamoichthys are 

 of much more ancient type than gars and sturgeons. (Ed. 18SG.) 



