THE DISCOBOLI. 



19 



FAMILIES AND GENERA OF DISCOBOLI. 



Body cavity elongate ; caudal region short ; 

 disk present ; teeth simple ; 



dorsals two ; skin tubercular, 



barbels none ; tubercles in rows, 



tubercles not in rows, 

 barbels present, 

 dorsal one, 



skin smooth ; dorsal short, 

 skin tubercular ; dorsal elongate, 

 Body cavity short ; caudal region elongate, 

 disk present, 



teeth tricuspid, simple in older Careprocti ; 

 caudal more or less distinct, 

 vertebrae less than forty, 

 vertebrifi more than forty-five, 

 caudal indistinct, tenuous ; 



teeth simple, at least in older stages, 

 disk absent, no ventrals, 



caudal indistinct, tenuous, 



CYCLOPTERID^. 



Anteriorly the form of the Lump-fishes is stout, thick, and deep ; behind 

 the body cavity, which occupies the greater portion of the length, it rather 

 abruptly becomes weak and slender. The head is short and broad, sub- 

 quadrangular in transsection ; the snout is short and blunt ; the mouth is of 

 moderate width, anterior, and opens shghtly upward; the teeth are small, 

 subconical, and arranged in a band or card ; the eyes are of medium size 

 and have a lateral outlook. All of the members of the family have pseudo- 

 branchifB, three and a half gills, six branchiostegal rays, small gill openings, 

 numerous pyloric ca3ca, and an elongate intestine. In their lower portions 

 the broad rounded pectorals extend forward under the throat, along the 

 sides of the disk. The vertical fins are not of large extent ; the caudal and 

 the two dorsals are quite separate. The disk is comparatively large. Early 

 in life the skin is tender and naked ; later it grows tough and is covered 

 with roughened or spine-bearing osseous tubercles. Semi-cartilaginous de- 

 scribes the skeleton with tolerable accuracy; the small amount of bony 



