BARBOUR, MATTHEW'S "CLIMATE AND EVOLUTION" 9 



Jamaica" and "Zoogeography of West Indian Eeptiles/' I have gone into 

 this matter in detail and there is no need of repeating what has been said 

 there. This homogeneity of the fauna is the best possible proof that 

 winds (tornados, hurricanes, etc.), birds, small floating drift, etc., have 

 played no considerable part in populating the island by carrying eggs or 

 adults, since it is inconceivable that by these means the same improbable 

 choice of passengers would be carried to so many islands. 



Matthew, upon the basis of the mammalian faima of Madagascar en- 

 tirely, he believes, derivable from a few waifs, and from the fact that the 

 island is not upon the present continental shelf, concludes that it is an 

 oceanic island. We may grant that all the lemurs have radiated from a 

 single type, and this may have been a waif type — all this for the sake of 

 argument — ^but what does the rest of the fauna show ? We find abundant 

 amphibians of many different families, as well as a great host of other 

 land and fresh water organisms which cannot by any stretch of the im- 

 agination be considered as more probably capable of surviving raft trans- 

 port than mammals, nor in very many cases of possibly surviving such 

 transportation at all. Yet such types as these are most abundant upon 

 Madagascar, in individuals and in species — species representing wholly 

 unrelated mainland stocks and not those which might possibly have arisen 

 after coming to the island. 



My friend Dr. Gr. M. Allen has contributed the following note regard- 

 ing Madagascar which is interesting in this connection. He writes me: 

 "The total absence from Madagascar of any native species of the typical 

 Murinse seems to be a striking bit of negative evidence against a chance 

 population of the island. All the nine genera of indigenous rodents are 

 Cricetine in their affinity, though now considered to represent a special 

 subfamily by themselves — Nesomyinae. The Cricetine-like rodents are 

 abundant still in the Americas, less so in number of species in northern 

 Eurasia. The African Lophiomys is nearly related. If we consider the 

 more specialized typical Murinse as representing a later development of 

 the Muridse, it is easy to accoimt for their absence from America, if for- 

 merly, as now, their northward range did not extend to the East Siberian 

 region, whence they could have crossed by land bridges if such existed. 

 That no member of so widespread and successful a type in the Old World 

 as Mus (in the broad sense) has reached Madagascar, it seems evident 

 that it is because none have been able to cross the intervening water. If 

 nine distinct genera of Cricetine-like rats or their ancestor or ancestors 

 could have reached Madagascar by chance methods, it seems inconceivable 

 that no single Murine could have done so, despite the great adaptability 

 and alnmdance of the representatives of this group. The most attractive 



