2. SICYASES. 405 



The lower jaw is short, anteriorly with four horizontal cutting teeth, 

 laterally with three small conical ones. The eye is rather small, 

 situated immediately below the upper profile of the head. Two 

 nostrils, close together, opposite to the upper angle of the orbit ; 

 the anterior has a short fringed tentacle. The lower angle of the 

 opercular apparatus (suboperculum) terminates posteriorly in an 

 acute point, enveloped in skin and directed backwards. The gill- 

 openings arc somewhat narrow, in consequence of the small degree 

 of expansibility of the gill-covers ; but the gill-membranes have the 

 margin quite free, being united together at the throat, and not 

 attached to the isthmus. There are only three gills ; the pseudo- 

 branchioe are quite rudimentary. 



The distance of the origin of the dorsal fin from the caudal is one- 

 half of its distance from the snout ; its first ray is much shorter than 

 the others and unarticulated ; but it can with as little reason be con- 

 sidered as a rudiment of a spinous portion as the same ray in. Cypri- 

 noid and other Malacopterous fishes. - The caudal fin is truncated 

 and of moderate length. The anal fin is shorter than the dorsal, 

 and situated more backwards, its origin falling in the vertical from 

 the eighth dorsal ray. The pectoral fin is broad and short, with tlie 

 posterior margin convex and with a large cutaneous fold antcriorlj- 

 on its base ; inferiorly it is verj* slightly connected with the ventral. 



The adhesive apparatus has only an external similarity to the 

 organ observed in Cyclopterus and Liparis ; its structure is typieulbj 

 different from it. Whilst in those genera the ventral fins occupy the 

 centre of the disk, forming its base, these fins are here wideiy apart 

 from each other, as in CaUioiojmus, forming only a portion of the 

 periphery of the disk, which is completed by a cartilaginous exi)an- 

 sion of the coracoid bones. I here attempt to give the following de- 

 tailed description orfts structiu'c. 



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 veritrals. 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 fringe is a fold of the skin, containing on each side tlie 

 rudimentary ventral spine, but no cartilage. The posterior peri- 

 pheric portion is suspended on each side on the coracoid, the upper 

 bone of which is exceedingly broad, becoming a free, moveable plate 

 behind the pectoral. A. broad cartilage is firmly attached to it. 

 The lower bone of the coracoid is of a triangular foim, and supports 

 a very broad fold of the skin, extending from one side to the other, 

 and containing a cartilage which nins through the whole of that 

 fold. Fine processes of the cartilage are continued into the soft 

 striated margin in which the disk terminates posteriorly. The sur- 

 face of the disk is coated with thick epidermis, like the sole of the 

 foot of higher animals. The epidermis is divided into many poly- 



