640 J. PLAYFAIR MCMUREICH. 



infra-orbital posteriorly, and the quadrate for some distance 

 anteriorly, is, on either side, a scale-like bone (figs. 12 and 13, 

 M.), which has no special representative in other Teleosts, and 

 is merely a membrane bone formed in the dense integument 

 closing in the buccal cavity below. 



The anterior process of the pterygo-qnadrate cartilage ossifies 

 as the pterygoid, its cartilage apparently passing forward to 

 become continuous with the ethmo-palatine. Anterior to the 

 pterygoid bone, bounding the mouth above, is the palatine, 

 an ectosteal bone developed upon the ethmo-palatine cartilage, 

 and on the outer side of this is a splint-bone, which bounds 

 the gape above, and which, from its relation to the ethmo- 

 palatine cartilage, must be the maxillary. The premaxillse 

 appear to be wanting, the maxillae bounding the gape. 



My sections of the mandibular region not being very good, I 

 am unable to make any statements concerning the ectosteal 

 bones of the mandible. The opercular bones are not present 

 in as great numbers as in typical Teleosts. There is a very 

 large operculum, somewhat scale-like and convex outwardly, 

 which articulates with the hyomandibular. The prseoper- 

 culum, a very constant bone in the Teleostei, here appears to 

 be absent, or at any rate very rudimentary. A membranous 

 suboperculum bounds the operculum below, and is continued 

 up behind it as far as the spiracular branchial cleft ; there is 

 no interoperculum. The outer surface of all bones upon 

 the surface is beautifully sculptured, some of the thinner ones 

 presenting an elegant fenestrated appearance. 



Summary. — In the first place, the great elongation of the 

 symplectic is very noticeable, and as a consequence there is a 

 wide separation of the hyomandibular and metapterygoid ele- 

 ments. The ethmo-palatine articulates with the sides of the 

 anterior extremity of the ethmoid or rostral cartilage, and 

 grows backwards to unite with the pterygoid process of the 

 pterygo-quadrate. In the adult the elongation of the posterior 

 mandibular region, and the concentration of the anterior por- 

 tion, are well marked. The great elongation backwards of 

 the metapterygoid and quadrate bones, the absence of any 



