/ VERTEBRATES : MAMMALS. 



MONODONTIM: OR NARWHAL FAMILY. This Family 

 contains only the Genus Monodon, and only one living 

 species, the Narwhal M. monoceros, Linn. 



The Narwhal has no true teeth, but a long, straight, 

 spirally furrowed and pointed tusk, implanted in the in- 

 termaxillary bone, and directed forwards in the line of 

 the body. This tusk is on the left side, and is eight or 

 ten feet long ; an undeveloped one exists on the right 

 side. Excepting the tusk the Narwhal resembles a por- 

 poise. Its home is in the Arctic Seas. 



SUB-SECTION VI. 



THE ORDER OF CHEIROPTERA, OR BATS. 



The Order of Cheiroptera comprises mammals whose 

 distinguishing characteristic consists in a fold of skin 

 which, commencing at the sides of the neck, and extend- 

 ing between the four members and fingers of the anterior 

 extremities, supports the animal in the air, and enables 

 it to fly. In most cases they have the arms, forearms, 

 and fingers excessively long, forming, with the membrane 

 mentioned above, true wings of great extent of surface, 

 so that they are able to fly long and rapidly, and execute 

 movements as varied and complicated as those of birds. 



Fig. 63. 



Hoary Bat, L. frmnosus, Say. 



Bats may be divided into two great groups, the Frugi- 

 vores and Insectivores, and these again into several fami- 

 lies, 



