OSTEOLOGY General. 



I. Skull. Tlie number of separate cranial bones is in 

 most Mammalia less than in Reptilia and Pisces. Tbe occi- 

 pital condyles are two in number, as in Amphibia, from 

 wbicb, bowever, tbey differ in development : the Mamma- 

 lian condyles being formed by the exoccipitah, in conjunction with 

 the well ossified basioccipital and not from tbe exoccipitals alone 

 (Amphibia). The foramen magnum is usually situated at the 

 back part of the skull, and generally in a position more or 

 less perpendicular (cf. i. and ii, 1).* Near to, or immediately 

 above it, there occasionally occur persistent fontanelles (cf. 

 vi, 4). The Paroccipital (= 'jugular process* in Man) 

 frequently exceeds the * Mastoid process' in size. The Sphe- 

 noid coalesces with the occipital at an early period. The 

 Parietals are usually small and insignificant, flat, and fre- 

 quently united together, obliterating the sagittal suture 

 (cf. V. vi. viii, 1. x, 2). An Interparietal bone is some- 

 times met with (cf. v. ix, xiv). The Frontalis generally but 

 slightly arched, and consists originally of two lateral portions 

 which not unfrequently remain distinct : sometimes a single 

 frontal bone is found (cf. i. ii, 1. iv. vii. viii, 2). The sutures 

 of the bones of the skull generally remain visible throughout 

 life, The Temporal bone consists in the foetus of four pieces ; 

 the squamous, the tympanic, the petrous, and the mastoid : 

 of these the squamous portion is for the most part low and 

 compressed ; icith it each ramus of the lotcerjaw directly articu- 



* These figures apply to the Orders and Sub-orders, as numbered in the 

 following section. 



