GENERA OF THE ARCIFEROUS ANURA. 109 



homologous divisions of the classes and subclasses, and not to the classes themselves. 

 Hence the relations between the two FaunjB will be those of differing minor epochs 

 in geological time, through several of which some special forms may range ; and we 

 may safely conclude, from data above alluded to, that the Regio Palseotropica is one 

 or more geologic epochs in advance of the R. Neotropica. 



Between these Faunae come the Nearctic and Palaaarctic, of which Agassiz has said 

 that the former was an epoch behind the latter. The undeveloped condition of our 

 predominant types of Salamanders, our Pleurodont Saurians, our more numerous 

 Clamatores and nine-quilled Oscines, and the comparative fewness of the ten-quilled 

 Oscines, especially the highest, Turdidse (including Sylviidoi), would indicate from 

 an anatomical stand-point that this view is correct, though the balance of difference 

 is small, and the northern regions are nearly identical. 



As to the Regio J^^thiopica, excepting of course Madagascar, in reptilian features it 

 is almost equivalent to the R. Indica ; in several points the southern extremity must 

 be excepted from this comparison. 



Of the R. Australis, Prof Agassiz* has said that none of its animal products present 

 that degree of peculiarity exhibited by the Mammalia. Its inferiority is plain, how- 

 ever, in the points below included ; and if we consider any distributions from the 

 centres to have taken place during brief epochs of time, this region will have had 

 every opportunity of acquiring its few high types, as some Acrodont Lacertilia, and 

 numerous birds,t which can be most readily transported ; including a few high 

 Oscines from its neighboring Pala3otropical area t 



On the whole, it cannot be said that the evidence for the succession here claimed 

 is as yet much more than fragmentary ; yet it appears to be sufficiently indicated, 

 which cannot be said of any other order or succession. 



The succession of the great regions and grounds therefore, may then be imper- 

 fectly illustrated as follows : 



R. Australi s. — Inferior in Monotrematous and Marsupial Mammalia, Pullastri- 

 form and Struthious Birds, Serpentiform Pleurodont Lacertilia, Arciferous Ba- 



* Contrib. I. 44 Prof. A. also gives a table of Scincidae from Dumeril and Bibron, illustrating its distribu- 

 tion, from which it would appear that the greater number of limbless and digitless types are from other regions 

 than the E. Australis. But of the twenty genera, with toes less than 4 — 4, but eight belong to the Scincida;. 

 Adding to these two from Gray's Catalogue, we have seven of them Australian, one South ^Ethiopian, one 

 Palaearctic, and one Palaeotropical. It possesses in addition the limbless families Pygopodidaa, Lialisidae, and 

 Aprasiidffi. It must at the same time be remembered that the most elevated Scincidse belong to the savie 

 region Cyclodus, Hinulia, etc. 



t Much must yet be allowed for the incompleteness of anatomical knowledge of the birds. The only system 

 which, in many features, appears to nearly accord with nature, is that published by Wilh. Lilljeborg. Upsala 

 Transactions, 1862. 



% Vide articles by A. AVallace on distribution in the Malaysian and Australasian Archipelagos. 



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