512 FISHES. 



and, as usual, composed of two pieces, the upper of which is 

 not suspended from the humerus, but fixed by a ligament to 

 the hinder margin of the carpal bones. It is a broad lamella, 

 dilated posteriorly into the cartilage, which is externally 

 visible ; the lower piece is narrower, and fixed to the extremity 

 of the pubic bone of its side. The pubic bones are united by 

 suture, and form together a heart-shaped disk, the point of 

 which is produced backwards. The anterior portion of the 

 disk is concave, with a bony longitudinal bridge and a feeble 

 transverse ridge. The disk is fixed to the humeral bones by 

 the convex portions of its anterior margin, whilst the convex 

 portions of the lateral margins serve as base for the ventral 

 fins. The latter are composed of one spine, which is trans- 

 formed into a broad, tliin, and curved plate, hidden below the 

 skin, and apparently of four rays ; but on closer examination 

 we find that the hidden ray has a longitudinal groove 

 anteriorly, in which another thinner ray lies concealed. 

 This ray is quite free, and not joined to the pubic bone. 



The fishes belonging to the single family of this division, 

 GoMesocidcB, are strictly marine but littoral fishes. They are 

 scattered over the temperate zones of both hemispheres, 

 and more numerous than between the Tropics. All are of 

 small or very small size. 



The adhesive disk consists of an anterior and posterior 

 division. In some of the genera the posterior division has no 



Fig. 232. — Gobiesox ceplialus. 



free anterior margin, the teeth being either all conical, as in 

 Chorisochisvius (Cape of Good Hope) and Cotylis (Eed Sea 



