MAMMALIA. CHIKOPTERA. 371 



this applies specially to the phalanges of all the digits except 

 the pollex. 



The pollex is clawed and so is sometimes the second digit ; 

 the other digits of the manus are without nails or claws. The 

 teeth are divisible into the four usual types and the series 



91 33 



never exceeds i ^ c -=- pm - w - x 2, total 38. The milk 



O 1 DO 



teeth are quite unlike the permanent teeth. The orbit is not 

 divided by bone from the temporal fossa. The vertebral 

 column is short, and in old animals the trunk vertebrae 

 have a tendency to become partially fused together. The 

 cervical vertebrae are remarkably wide, and the development 

 of spinous processes is everywhere slight. The presternum 

 has a prominent keel for the attachment of the pectoral muscles. 

 The clavicles are very long and strong, and the scapula has a 

 long spine and coracoid process. The ulna is vestigial, con- 

 sisting only of a proximal end ankylosed to the radius. All 

 the carpals of the proximal row the scaphoid, lunar and 

 cuneiform are united, forming a single bone. The pelvis is 

 very weak and narrow, and only in the Rhinolophidae do the 

 pubes meet in a symphysis. The anterior caudal vertebrae are 

 frequently united to the ischia. The fibula is generally ves- 

 tigial, and the knee joint is directed backwards instead of 

 forwards. The pes has five slender clawed digits, and the 

 calcaneum is often drawn out into a spur which helps 

 to support the membrane connecting the hind limbs with the 

 tail. 



There are two suborders of Chiroptera : 



1. The MEGACHIROPTERA or Flying foxes, which almost 

 always have smooth crowns to the molar teeth, and the second 

 digit of the manus clawed. 



2. The MICROCHIROPTERA including all the ordinary bats 

 which have cusped molar teeth, and the second digit of the 

 manus clawless. 



242 



