GOBIESOCID^. 511 



Wliilst in those genera the ventral fins occupy the centre of 

 the disk forming its base, these fins are here widely apart 

 from each other, as in Callionyimis, forming only a portion of 

 the periphery of the disk, which is completed by a cartila- 

 ginous expansion of the coracoid bones. The following 

 description of its structure is taken from Sicyases sanguineus, 

 but it is essentially the same in all the genera. 



The whole disk is exceedingly large, subcircular, longer 

 than broad, its length being one-third of the whole length of 

 the fish. The central portion is formed merely by skin, 

 which is separated from the pelvic or pubic bones by several 

 layers of muscles. The peripheric portion is divided into an 

 anterior and posterior part by a deep notch behind the 

 ventrals. The anterior peripheric portion is formed by the 

 four ventral rays, the membrane between them, and a broad 

 fringe which extends anteriorly from one ventral to the other ; 

 this frmge is a fold of the skin, containing on each side the 

 rudimentary ventral spine, but no cartilage. The posterior 

 peripheric portion is suspended on each side from the 

 coracoid, the upper bone of which is exceedingly broad, be- 

 commg a free movable plate behind the pectoral. A broad 

 cartilage is firmly attached to it. The lower bone of the 

 coracoid is of a triangular form, and supports a very broad 

 fold of the skin, extending from one side to the other, and 

 containing a cartilage which runs through the whole of that 

 fold. Five processes of the cartilage are continued into the 

 soft striated margin in which the disk terminates posteriorly. 

 The surface of the disk is coated with thick epidermis, like 

 the sole of the foot of higher animals. The epidermis is 

 divided into many polygonal plates ; there are no such plates 

 between the roots of the ventral fins. 



Not less unique is the structure of the bones which have 

 some relation to this external adhesive apparatus. As exempli- 

 fied by CJiorismochismus dentex the coracoid is well developed, 



