RATS ON GALAPAGOS ISLANDS 299 



Oryzomys galapagoensis he found a second distinct form 

 which he named Oryzomys bauri. 



A more important natural history survey of the islands 

 was made by the Hopkins Stanford Expedition in 1898. In 

 addition to the mammals already known from the archipelago, 

 it was discovered that Narborough, Indefatigable and Sey- 

 mour islands are inhabited by rice-rats, which show such 

 structural distinctness in the interorbital portion of the skull 

 that Mr. Heller * proposed their being placed into the 

 new genus " Nesoryzomys." Pour mouse-like mammals are 

 thus known to be peculiar to the Galapagos islands, viz., 

 Oryzomys galapagoensis, 0. bauri, Nesoryzomys indefessus 

 and N. narboroughi. The only other terrestrial mammal not 

 found elsewhere is Atalapha or, as it is now called, 

 Lasiurus brachyotis. 



It is interesting to note that the genera to which these 

 species belong are characteristically American. Both Ory- 

 zomys and Lasiurus have a wide range in North and South 

 America as well as in the Antilles. We have learned that 

 Oryzomys antillarum is confined to Jamaica. Another species 

 lives on St. Vincent, and several more on Trinidad, while a 

 species (0. nelsoni) is peculiar to the Tres Marias islands off 

 the west coast of Mexico. A genus ranging from New Jersey 

 in the north to Tierra del Puego in South America, with a 

 large number of species, must be a very ancient one; and 

 yet not a single species occurs outside the New World. 



I have never hitherto alluded to bats because they are so 

 generally regarded as of little value in faunistic problems. 

 Specialists of this group, such as Dr. Knud Andersen,f in- 

 form us, however, that this assumption is by no means correct, 

 and that in most cases bats are as good and reliable zoogeo- 

 graphical guides as other small but non-flying mammals. 

 The fact that although Lasiurus is found from Canada to 

 Patagonia it has nevertheless preserved its original habitat 

 in the New World, and has not even crossed Bering Strait into 

 Asia, would seem to support Dr. Andersen's contention, while 

 its antiquity is vouched for by the occurrence of distinct 

 species of Lasiurus on several remote American islands. 



* Heller, Edmund, " Mammals of Galapagos Archipelago." 

 t Andersen, K., " Geogr. Distribution of Ehinolophus," p. 652. 



