592 BATS xxii. 2- 



formed at birth and have then already cut the milk dentition of special 

 teeth, with sharp, backwardly directed hooks, which, with the claws, 

 enable the baby to remain attached to the mother in flight. Most bats 

 live massed together in colonies during the day, with a considerable 

 social organization. They spread out at night and home accurately. 

 After artificial displacement marked bats return home from ioo km or 

 more. Some species hibernate in large colonies where there are suitable 

 caves and then migrate for 1,000 km or more and return to the same 

 cave next winter. 



The Megachiroptera, fruit bats or flying foxes, are quite large 

 animals (with wing span up to 5 ft.) living in Asia, the Pacific, Aus- 

 tralia, and Africa. In spite of their diet they are in some ways the 

 less-specialized group, having a snout, head, and ears of normal 

 mammalian form. 



The Microchiroptera is one of the most successful groups among 

 modern mammals, including a large number of families, genera, and 

 species, with differing habitats. As would be expected, the families 

 often have wide geographical ranges, vespertilionids, for instance, are 

 found all over the world. It is interesting, however, that the genera 

 mostly have a rather restricted range. For instance, Vespertilio is 

 limited to the Palaearctic, though Pipistrellus is found also in North 

 America. The vampire bats (Phyllostomatidae) are restricted to Central 

 and South America. The fact that even flying mammals should be so 

 restricted is good evidence that the simple problem of communication 

 is one of the least of the difficulties standing in the way of the dispersal 

 of an animal type. 



3. Order Dermoptera 



The colugo or flying lemur of the orient, correctly called Cyno- 

 cephalus (— Galeopitheciis), was probably an early offshoot from the 

 insectivoran stock, with a patagium developed for parachuting. The 

 wing differs from that of bats in that the fingers are not elongated and 

 the wing is not flapped. The animals are nocturnal and feed on leaves 

 and fruit. A peculiarity is the forwardly projecting lower incisors with 

 tips divided to form a comb, as in lemurs. A related Palaeocene form 

 shows that this line has been separate for more than 50 million years. 



4. Order Edentata 



Cohort Unguiculata 

 Order 6. Edentata 

 ^Suborder 1. Palaeanodonta. Palaeocene-Oligocene. N. America 

 *Metacheiromys, Eocene 



