18 THE DISCOBOLI. 



the slightest. Certain species possess two dorsal fins; on others the two are 

 more or less perfectly confluent, and on some the spinous dorsal would seem 

 to have been lost. The head is short and broad, the snout blunt and rounded, 

 and the mouth, small to moderate, is auterior. The teeth are small, either 

 subconical or tricuspid, and the number of series in function varies fiom 

 a couple to half a dozen or more forming a pavement. In some cases the 

 eyes are very small, in others they are of moderate size ; their direction is 

 lateral or obliquely upward. Quite generally there are six branchiostegal 

 rays ; so far as we know there are no exceptions to thjs nimiber. The gill 

 openings are rather narrow to very narrow ; sometimes they extend down- 

 ward upon the bases of the pectorals, but often they are situated entirely 

 above the fins. The gill membranes are united with the isthmus and the 

 shoulders. Usually there are pseudobranchia3 in addition to the three gills 

 and a half; they are said to be absent in a particular species. None of the 

 Discoboles possess air bladders. The stomach is siphonal, and bears a cluster 

 of casca around the side of the pylorus. The skeletal structure is almost 

 cartilaginous in Cyclopterus, the osseous matter being small in quantity and 

 arranged in thin plates, forming chambers as in Lophius ; from this it varies 

 to more solid and firm in species of Liparis. Throughout the genera the 

 operculum, the suboperculum, and the interoperculum are reduced in size; 

 most so perhaps in some Liparididte, where these bones are slender and 

 spine-like. On Cyclopteridas they are thin, but broader and more like 

 blades. A common feature of the Discoboli is the prolongation of the third 

 suborbital bone to the preoperculum across the cheek. The Lumps have 

 this suborbital rather broad, thin, flexible, and slightly drooping backward ; 

 on certain Liparids it is slender, styliform, nearly straight, and extends to 

 the hinder edge of the preopercle. 



The following synopsis includes the known members of the group. 



