338 ZOOLOGY. 



presents behind a cranial cavity (c), lodging the organ of 

 hearing as well as the brain. About the middle are the orbitar 

 ravitirs (or), and anteriorly, the cavities belonging to the 

 olfactory apparatus (n) and a kind of large prominence formed 

 by the vomer, and supporting the upper jaw (Fig. 309 v). 

 The analogues of the occipital, temporal, sphenoidal, parietal, 

 frontal, ethmoidal, and vomer may readily be recognised, 

 but most of these parts are composed of several pieces, the 

 original germs of these bones, which never unite in fishes. 



Anteriorly, is found the upper jaw, which is sometimes 

 fixed, but more usually very moveable ; on each side are an 

 intermaxillary bone (im) and a maxillary bone (m), which is 

 moveable on the first. 



A chain of small bones extends on each side from the ante- 

 rior angle of the orbit to the posterior, and thus completes 





t p io 

 Pig. 308. Bone of the Head of the Pike.* 



the orbitar circle. Deeper may be seen on each side a kind 

 of vertical partition suspended to the cranium, and separating 

 the orbits and cheeks from the mouth. It is formed by the 

 analogues of the palatine, pterygoids, tympanics, &c., and 

 articulates with the cranium by two points (on the vomer 

 and temples). Inferiorly it gives attachment to the lower jaw, 

 posteriorly it is prolonged so as to form a moveable covering, 

 called the gill cover. Three bones on each side form the 

 lower jaw, which articulates by a concave surface with the 

 jugal apparatus, just described; finally, an assemblage of 



* c, cranium or orbit ; n, nasal fossae ; im, intermaxillary bone ; m, supe- 

 rior maxillary bone ; t, a kind of lateral partition separating the cheek from 

 the mouth, and which articulates forward with the vomer by means of the 

 palatine arches, above with the cranium (c), below with the lower jaw, l>phiml 

 with the pre-operculum (p), which, in its turn, supports the operculum (op) ; 

 to, the pre-operculum bone, followed by the sub-operculum. 



