MAMMALS OF MINNESOTA. 23 



The form of the skull is extremely variable and affords a 

 safe guide to the habits of the various species. Compare, for 

 instance, the skulls of Chceronycteris and Chilonycteris. Most of 

 the true bats have no post orbital frontal processes. The nasals 

 are generally short and vary much in form. The most re- 

 markable differences are found in the form of the pre-maxillary 

 bones. In EhinolopMdce, they are rudimentary. The zygo- 

 mas are well developed in the flying foxes, but are wanting in 

 several species of true bats. The auditory bullae are usually 

 large and well developed. The vertebral column is short. The 

 dorsal vertebrae number twelve or thirteen. The caudal verte- 

 brae are cylindrical, without processes. There are also no 

 spinous processes upon the cervicals and dorsals. The clavi- 

 cles are strong and curved. The scapula is large, the post 

 scapular fossa being much the larger, the spine is large, as are 

 the acromium and the coracoid. Although tne humerus is 

 long, it is greatly exceeded by the bones of the forearm and 

 all these bones have large medullary cavities. The ulnar is 

 rudimentary; the scaphoid, lunar and cuneiform bones are 

 united. 



The thumb terminates in a claw as does the index in many 

 forms. The pelvis is weak. The pubic bones are widely sep- 

 arated in the females. The fibula is often rudimentary. The 

 calcaneum forms a long cartilaginous process or spur which 

 supports the interfemoral web. The sensory apparatus, al- 

 ready referred to, consists of several peculiar foliaceous expan- 

 sions about the nose and ears as well as the ordinary organs. 

 Aside from these are glandular appendages near the muzzle 

 covered with fine tactile hairs like the vibrissae of other ani- 

 mals. The ears are also greatly developed, with membranous 

 expansions and fringing appendages in many species. Each 

 ear is movable independently. The lips are often curiously 

 modified and are "very sensitive. The alimentary canal is quite 

 complicated in the frugivorous bats but has the ordinary car- 

 nivorous structure in entomophaga. The liver is always large. 



For farther details regarding the anatomy the reader is re- 

 ferred to the discussion of our native species. 



Here it may "not be amiss to pass in review a few of the more 

 important families and genera. 



It is common, first of all, to divide the Chiroptera into two 

 sub-orders. Sub-order Carpophaga or the fruit-feeding bats 

 embraces the flying foxes and includes but the single family 

 Pteropodidce. 



