220 



FIB8T LE8S0N8 IN ZOOLOGY. 



upper arm, a fore arm, and a paw, with five short toes. The 

 hind limbs each consist of a thigh, a leg, and a foot with 

 but four toes. The elbow' and knee are close to the trunk. 

 It is so with the dog. The legs of the ox and horse do not 

 project from the body above the knee or elbow; those of the 

 monkeys project two thirds of their length, while the limbs 

 of man are wholly free from the trunk. 



Fio. 226.— Side-view of the cat's skull, the lower jaw and hyoid bone (tft, f*]j being 

 detached, a, aJlsphenold bone; a<^^ external auditory canal; a?*, ascending ra- 

 mus; 6, auditory bulla; c, occipital condyle; /, frontal; tj), interparietal; j, 

 malar or jugal; kt, lachrymal; in^ maxilla; ins^ mastoid _process; 7i, nasal; o&^ 

 orbito-sphenoid; p, parietal; pa, palatine; pt, pterygoid; pm, premaxilla; s, 

 squamosal; so, supraoccipital; z^ zygoma; 2, infraorbital foramen; 6, optic 

 foramen. 



Opening the mouth, we see that it is lined with a soft, 

 delicate wet skin called mucous membrane, while the jaws 

 contain teeth. A full-grown cat has thirty teeth, or fifteen 

 on each side of the head, but two more in the upper than 

 in the lower jaw. 



We haye seen that in reptiles the teeth are conical and 

 much alike, but in the eat and other mammals there is a 

 great difference h^^ *\\s, teeth of different parts of the jaw. 



