x.] MAN. 159 



with the tympanohyal, commences to ossify by a separate 

 centre before birth, and, at a very variable period after- 

 wards, is often (but by no means constantly) ankylosed 

 with the tympanohyal and surrounding cranial bones, con- 

 stituting the so-called " styloid process." This is a con- 

 dition not met with in any other Mammal. Below the 

 stylohyal the greater part of the anterior hyoid arch is 

 represented by a slender ligament (the " stylohyoid " liga- 

 ment), there being no ossification corresponding to the 

 Dog's epihyal ; but the ceratohyal (ch) to which the liga- 

 ment is attached below, is a small bony nodule, the 

 '* lesser cornu of the hyoid ' : of human anatomy, which 

 is articulated synovially to the upper corner of the 

 outer extremity of the basihyal, though sometimes in old 

 age becoming ankylosed. The basihyal (<//), or "body 

 of the hyoid," is transversely oblong, hollowed posteriorly, 

 and deeper from above downwards than in the Dog. The 

 thyrohyals (t/i) or "greater cornua of the hyoid," are elon- 

 gated, nearly straight and somewhat compressed. They 

 usually become ankylosed before middle life with the outer 

 extremities of the basihyal. 



The remainder of the true Primates (Simiina, or Monkeys) 

 have the skull formed generally on the same plan as that 

 of Man, with certain modifications in detail. 



The facial portion is enlarged and elongated as compared 

 with the cerebral potion, though to a very variable extent 

 in different members of the group. 



In nearly all, the brain-cavity maintains the same general 

 form as in Man, though it is usually of less comparative 

 vertical extent. With few exceptions, the middle compart- 

 ment for the lodgment of the cerebrum retains its 

 relative situation and superiority in size to the cerebellar 



