MATTHEW, CLIMATE AND EVOLUTION 237 



took a much more important place in the mammahan faunae of the world 

 than it does now. This shoukl be kept in mind in considering the rela- 

 tions of tlie Insectivora. 



CHIKOPTEKA 



I am not sufficiently acquainted with modern Chiroptera to venture 

 an opinion as to whether or not their geographical distribution indicates 

 their place of origin, but I should not expect to find much satisfactory 

 evidence, as they are known to be of very ancient specialization and to 

 have gi-eater facilities for wide distribution than terrestrial animals. 



Dr. Andersen,^^ in his recent Catalogue of the Chiroptera in the 

 British Museum, remarks: "The evidence afforded by the geographical 

 distribution of Bats has generally been considered of doubtful value; 

 hence they have either been entirely excluded from the material worked 

 out by zoogeographers, or at least treated with pronounced suspicion as 

 likely to be more or less unreliable documents of evidence. This un- 

 willingness or hesitation to place Bats on an equal zoogeographic footing 

 with non-flying Mammalia would seem to be due partly to the precon- 

 ceived idea that owing to their power of flight Bats must evidently have 

 been able easily to spread across barriers which in ordinary circumstances 

 are insuperable for wingless Mammalia; partly to the fact that hitherto 

 very often whole series of distinct forms have been concealed under one 

 technical name. . . ." [the author cites a series of instances of this 

 kind which] "tend to show that the present distribution of the Mega- 

 chiroptera has not been influenced to any great, and as a rule not to 

 any appreciable extent by their power of flight; if it had the Fruit-bat 

 fauna of islands could not so commonly as is actually the case differ 

 from that of a neighoring group or continent, and the tendency to dif- 

 ferentiation of insular species or forms would have been neutralized by 

 the free intercourse between neighboring faunas." 



The belief that bats are more easily able to cross ocean barriers than 

 non-flying mammals is probably based, not on the preconceived idea that 

 they could, but upon the plain fact that they have done so far more 

 frequently. Birds and bats are found upon numerous oceanic islands 

 where no non-flying mammals, and very few non-flying animals at all, 

 exist. That they have wings and occasionally use them for so long a 

 journey, whether voluntarily or involuntarily, is a natural explanation. 

 I cannot see any other reasonable intei-pretation of the fact that they 

 are present and the terrestrial mammals absent in so many remote oceanic 



*s K. Andersen : Catalogue of the Chiroptera in the British Museum, Vol. I, Megachi- 

 roptera, p. Ixxvi. 1912. 



