34 BRITISH BATS. 



a good idea of the so-called wings of the bat, by 

 stretching our arms to their full extent, imagining 

 the thumb changed into a hook, and the fingers 

 elongated to the length of several feet, having a 

 soft leather-like substance attached to the body, 

 and so enveloping their extreme tips. To support 

 this extent of wing the clavicles are long and arched 

 in form, being firmly attached to the sternum and 

 scapulae the vertebral formula in Vespertilio pipis- 

 trellus is as follows : 7 cervical, 12 dorsal, 7 

 lumbar, 3 sacral, and 12 caudal vertebrae. The 

 sternum is very long, and there is a bony keel in 

 the centre for the attachment of the powerful 

 muscles that move the wings ; the ribs are ex- 

 tremely long, and considerably arched, so as to 

 afford plenty of space for the action of the thoracic 

 viscera. The teeth in the insectivorous Cheiroptera 

 are studded with sharply pointed tubercles, and the 

 jaws are only capable of vertical motion. In the 

 formation of the skull the occipital condyles are 

 subterminal, the super- occipital slope backwards, 

 and join the crista, continued forwards by the 

 interparietal and parietal bones. The occipital 

 foramen is very large. The premaxillaries are ex- 

 tremely small ; in one of our British species, the 

 great horse-shoe bat (Rliinolophusferrum equinum), 

 they are wanting. By means of the sharp claws of 

 the hind feet, and the hook-like projection on the 



