142 GOBIIDiE. 



(f. Adult male : skeleton : not good state. Purchased. 



\. Adult male : skeleton. Polperro. Presented by J. Couch, Esq. 



Skeleton. — The skeleton of Callloni/mus resembles that of the 

 typical Gohiina with regard to the form of the cranium and the 

 thin osseous layers of the single bones, but shows several very re- 

 markable peculiarities : — 



1, in the structure of the facial bones ; 



2, in the arrangement of the opercular bones ; 



3, in the structure of the humeral arch ; 



4, in the three joints between occipital and first vertebra, situated 

 on the same horizontal line ; 



5, in the small number of vertebrae. 



The great protractiHty of the jaws is effected by the extreme pro- 

 longation of the processes of the intermaxillary bones ; they are 

 much longer than the body of the bones, moving in a broad shallow 

 groove formed by the ethmoid, nasal and praefi'ontal bones, and ex- 

 tending backwards in a cavity of the interorbital space. They are 

 shghtly curved, so that when the upper jaw is protracted, it assumes 

 a downward direction. The maxillary is shorter than the inter- 

 maxillary and scarcely dUated ; its extremity is received in a shallow 

 groove formed by a vertical ridge of the posterior portion of the 

 mandibula. The mandibles are long, slender, the symphjsial angle 

 being rather acute. The prseoi-bital is thin, very long, extending 

 nearly to the end of the snout ; infraorbital bones none. The an- 

 terior part of the vomer projects into the mouth, and its body is 

 rather broad and flat, tapering posteriorly. The pterygoid bones are 

 very narrow, the pretymj^anic and mesotympanic very small, leaving 

 a very wide and free space below the large orbit. The hypotym- 

 panic is elongate, and has a very strong longitudinal crest ; it is as 

 long as the prseoperculum ; the latter has no ascending, only a hori- 

 zontal, limb, the former part being entirely replaced by the epitym- 

 panic ; immediately behind the epitympanic there is the narrow 

 operculum, which is much smaller than the suboperculum. The sub- 

 operculimi is similar in form to an operculum, and occujiies the space 

 in which, in other fishes, the latter bone is usually found ; it is very 

 thin, striated, and has the margin fringed. The interoperculum is 

 continuous with the suboperculum, forming a narrow, thin, elongate 

 lamella. 



The hyjiotympanic and the prseoperculum are provided with a 

 bony keel or crest, which extends from the jouit of the mandible to 

 the base of the prceopercular spine ; another bony keel runs down- 

 wards from the joiut of the epitympanic to the same spot, meeting 

 the fii'st keel at an acute angle. It is e\ident that these two keels 

 serve to support the pra3opercular spine : this would have been far 

 less the ease if they had met at a right angle ; but in the direction 

 in M'hich they are placed, they answer fully the same purpose as 

 that peculiar process which is foimd on the cheek of the true Cottoids. 

 BrauchiostcgaLs filiform. 



The crown of the head is rather flat, about twice as broad as long, 



