486 DR. W. G. IIIBEWOOD ON THE CRANIAL [DeC. 13, 



Mandihular Series (text-tigs. 141 and 142).— The mandible is 

 of remarkable shape, since the anterior part is quite thin, having 

 the form of a curved rod, whereas the coronoid pi-ocess is broad 

 and stands high. The coronoid process is formed entii'ely by the 

 dentary, there beirig no ascending process of the articular. A 

 sesamoid articular is present ; it lies above the anterior part of 

 the endosteal articular, and is slightly movable in a wet pre- 

 paration. The angular is distinct from the articular. There are 

 no teeth. 



Text-fig. 142. 



hnv' 

 sy- 



Chunos salmonsns, liyopalatiue arch and luaiidiblo of left side, luesial aspect. 

 For explanation of lettering see p. 493. 



llyopalatine ISeries (text-fig. 142). — The hyomandibular arti- 

 culates with the cranium by a single broad head, the upper edge 

 of which, instead of being horizontal, slopes downward and forward. 

 In I'elation with the i-eduction in the size of the mouth, tlie 

 cpiadrate has been drawn so fai- forward as to have parted fi'om 

 the symplectic and metapterygoid entirely, and it is attached 

 to the ectopteiygoid in such a way that a fair proportion of 

 this bone lies behind it. The hyomandibular appears to be but 

 little affected, and its axis is nearly vertical. There is an angle 

 of about 110 degrees between the axes of the symplectic and 

 hyomandibular. No teeth occur on the palatine and pterygoid 

 bones. 



Opercular Series (text-fig. 141, p. 485). — The opercular and sub- 

 opercular bones are of a.vei'age proportions ; the ascending process 

 of the subopercular which rises along the fi'ont edge of the opei'- 

 cular is high and slender. There ai-e only foui- branchiostegal rays 

 on each side. They ai-e long, and rathei' broad and lamellate. Two 

 are attached to the outei- face of the posterior part of the cerato- 

 hyal, and two on the outer face of the epihyal. On examining 

 the skull of Ghanos, one cannot fail to be impressed by the regular 

 manner in which the biunchiostegal rays gi'ade oft' into the 

 opercular and suboperculai- bones, whereas the pi-eopercular and 

 interopercular fail to fit into the series. 



Hyobrcmchial Series (text-fig. 143, p. 487). — The most striking 

 features of the hyobranchial skeleton are the smallness of the hyoid, 



