THE MORMTBIDiE, NOTOPTEEID^, AND HTODONTIDiE. 191 



are fused at the symphysis, and the suture is obliterated. Each 

 bears thirteen or fourteen teeth, stout, bluntly pointed and 

 slightly curved. The sesamoid articular is distinct, and is set 

 rather liigher up the articular than is usually the case. There 

 is no separate angular bone. 



Eyopalatine Series (figs. 1 and 4). — The opercular head of the 

 hyomandibular is extremely short. The hyomandibular, strictly 

 speaking, articulates with the cranium by two heads, the 

 posterior about four times as broad (antero-posteriorly) as the 

 anterior ; but in the dried skull, in which the synovial cartilage 

 has shrunk up, the distinction is no longer visible, the upper 

 edge is nearly straight, and does not stand at a higher level than 

 that of the metapterygoid, which is in fibrous union with the 

 lateral edge of the parasphenoid. Indeed, the hyopalatine arch 

 is united with the cranium by the wliole of its upper edge, and 

 is separable from it with difficulty. In relation, doubtless, with 

 the length of the head, the axis of the hyomandibular slopes well 

 forward, the metapterygoid is about twice as long as high, and 

 the quadrate is drawn out to a considerable length in an antero- 

 posterior direction. There is no separate symplectic, and no 

 separate entopterygoid ; the palatine is small and fused on to 

 the side of the vomer. There are no teeth on the palatine or 

 pterygoid bones. 



Opercular Series (figs. 1 and 4). — The opercular bone is nearly 

 rhombic in shape ; the subopercular is small and triangular, and 

 concealed in an external view by the lower part of the opercular 

 bone. 



The branchiostegal rays are seven in number on each side ; 

 the first four are slender, curved rods, but the fifth and sixth are 

 slightly expanded at their posterior ends. The first two are 

 attached to the hinder part of the ceratohyal, and the next three 

 to the lower edge of the epihyal, although, on account of a 

 process of the ceratohyal which projects backwards on the outer 

 face of the epihyal, they appear to arise from the ceratohyal 

 when examined in an external view. The last two, which are 

 shorter than the fifth, are free from the epihyal, but lie close 

 alongside the ventral edge of the opercular bone. 



HyohrancJiial Series. — The interhyal is cartilaginous. The 

 anterior part of the hyobranchial skeleton is very aberrant. 

 There is no separate hypohyal ; but firmly fixed in between the 

 urohyal below and the dentigerous membrane-bone above is a 



