Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 105 



the small foramen for the glossopharyngeus, the cerebral opening 

 of which always lies in the lateral surface of the saccular groove. 

 In front of and above these two foramina, and occupying a large 

 part of the anterior edge of the lateral surface of the bone, is the 

 sharply defined and slightly depressed region that lodges the over- 

 lapping intercalar. The lower edge of the latter bone is, in turn, 

 overlapped externally by a thin, but relatively long and broad, 

 splint-like process of the occipitale laterale. 



The dorso-posterior surface of the bone lies nearly at right 

 angles to the ventro-lateral surface, the two being separated by the 

 strong, postero-lateral edge of the bone and skull. The surface 

 is traversed, at about its mesial third, by a ridge, which runs up- 

 ward, forward, and slightly laterally, and separates the surface 

 into two regions, a lateral and a mesial one. This ridge rises but 

 little above the outer level of the lateral portion of the surface, but 

 lies considerably above the level of the mesial portion, the latter 

 portion forming, accordingly, a depressed region, or groove, which 

 is continuous with the groove already described on the posterior 

 surface of the exoccipitale. The ridge marks the position of the 

 posterior semicircular canal of the ear. 



The dorso-lateral surface of the bone is continuous with the 

 mesial edge of the dorso-posterior surface, and lies approximately 

 at right angles to it. It is slightly convex, and that part of the 

 bone that forms its dorsal half is simply a thin shell which arches 

 over the anterior, intracranial end of the spinal cord, and forms, 

 with its hind edge, the dorsal and lateral boundaries of the fora- 

 men magnum. The ventral edge of this part of the bone, lateral 

 to and below the foramen magnum, is thickened, looks postero- 

 ventrally, and rests upon the basioccipital, as already described. 

 At the upper end of this thickened portion, at about the middle 

 of the hind edge of the bone, and at the level of the dorsal surface 

 of the vertebral column, there is a long, oval articular facet, which 

 occupies the ventro-postero-lateral surface of a slight condylar 

 eminence. The long axis of the facet inclines downward, forward 

 and laterally, and the facet itself, which is presented ventrally and 

 postero-laterally, articulates with a corresponding surface on an 

 anterior process of the first vertebra. It is covered with a thin 

 layer of tissue which is, to all appearance, fibro-cartilage. Dorso- 



