THE EABOONS. 25 I 



World Monkeys ; their tympanic (or ear) cavity being close to 

 the outer wall of the skull. The line of junction (or suture) 

 between the upper jaw-bones, the pre-maxillary and the max- 

 illary, remains unclosed until long after the permanent teeth 

 have come in. Sometimes it remains unclosed throughout 

 life. The foramen for the passage of the spinal-cord, and the 

 condyles for the articulation of the skull with the neck, he far 

 back. 



In the spinal column there are nineteen dorsal and lumbar 

 vertebrae together. The number of caudal vertebrae varies 

 greatly ; in some there are as many as thirty-one, in others 

 only three. The posterior ends of the ischiatic bones of the 

 pelvis are rough, flattened, and broad, for the attachment of 

 the fleshy callosities mentioned above. 



The bones of the thigh and leg {femur and tibia) together, 

 are longer than those of the arm and fore-arm {humerus and 

 radius) together. The bones of the thumb are modified 

 more for support and progression than for the actions of a 

 true hand ; by these modifications the movements of rotation 

 (pronation and supination) are much restricted. 



The ankle {tarsus) does not exceed one third of the length 

 of the foot. 



The stomach is simple, or but very slightly sacculated, in 

 those genera which possess cheek-pouches; but is tripartite 

 — the middle compartment being sacculated — in those that 

 have not store-pockets in their mouths, "a groove with raised 

 edges leading from the gullet-entrance to this middle com- 

 partment." The intestine has a caecum, or blind diverticulum. 

 " When laryngeal air-sacs are developed, they are formed by a 

 single sac, with a median aperture — immediately beneath the 

 epiglottis. This median air-sac is very large, extending down 



