CETACEANS. 



59i 



largest bats are the fruit bats or flying foxes (Ptero- 

 pus) of the East Indies ; one species of which expands one 

 and a half metres (nearly five feet) from tip to tip of the 

 wings. Our commonest species is 

 the little brown bat, Vespertilio 

 sululatus of Say ; nearly as com- 

 mon is the red bat, Atalapha no- 

 veboracensis Coues. 



Order 5. Cete (Cetacea).WQ 

 now come to the Educabilia, in 

 which the brain is more highly de- 

 veloped, and begin with two very 

 aberrant orders, the whales and 

 Sirenians, in which the body is 

 fish-like, though the tail is hori- 

 zontal ; the pelvis and hind limbs 

 are wanting, either wholly, or mi- 

 nute rudiments may be present ; 

 and they are aquatic, occasionally 

 leaping out of the water, but usu- 

 ally only showing the dorsal fin or 

 nose when at the surface to breathe. 



The whales and porpoises have 

 a large, broad brain, with numer- 

 ous and complicated deep convolu- 

 tions. 



In the skull (Figs. 512, 513) the 

 aperture for the spinal cord (fora- 

 men magnum] is entirely posterior 

 in situation and directed some- 

 what upward. The lower jaw is 

 straight, with no ascending ramus, 

 the narrow condyles being situated 

 at the end of the jaw, at the point j 



V.TT fV, rt on/Trlo /-vf +1-,^ yaTvmo whale, longitudinal section snow- 

 by the angle ol the ramus ing th ' e re f ative 8ize and form of 



mammals. The teeth are the cranial cavity, m^maxilla ; 



5 i 3 .-skuii of the sperm 



e, longitudinal SCCtion 8I1OW- 



' 



n 



prem axiii a .-After Flower. 



conical, with a single root, but are 



sometimes wanting. There is no neck ; the cervical verte- 



brae are sometimes confluent, forming a single mass. The 



