S CORP A EN I FORMES 



453 



the flying-fish, Exocoetus, present a most interesting case of convergence of 

 structure (p. 402). 



Dactylopterus, Lac, the Flying Gurnard (Fig. 473) ; Atlantic and 

 Indian Ocean. 



Family Hexagrajimidae. With an eye-muscle canal, rather smooth 

 cranial bones, few spines, and a continuous or incompletely divided 

 dorsal. The posterior nostril is reduced to a minute pore. Scales small. 



Hexagrammus, Steller ; Pleurogrammus, Gill ; Ophiodon, Gir. ; Zanio- 

 lepis, Gir. — N. Pacific. 



Family Comephoridae. Without eye-muscle canal, with few and 

 feeble spines. With very large pectoral, and small or no pelvic fins. 

 Oomephorus, adapted to deep waters, is colourless, and has very large 

 eyes ; moreover, the suborbital stay is reduced, and the whole skeleton 

 very delicate. 



Anoplopoma (Scombrocottus), Ayres ; N. Pacific. Triglopsis, Gir. ; 

 deep Canadian lakes. Oomephorus, Lac. ; Cottocomephorus, Pell. — Lake 

 Baikal. 



Fig. 474. 

 Cottus gobio, Cuv., the Miller's Thumb. (From Seeley, Freshwater Fishes of Europe.) 



Family Rhamphocottidae. With spiny cranial bones and incom- 

 plete cuirass, no myodome, and gills reduced to three and a half, with 

 narrowed opening. The flat post-temporal is fixed to the skull. Small 

 spiny scales. Vertebrae few (24). 



Phampliocottus, Gthr. ; Pacific coast of N. America. 



Sub-Tribe B. The scapula is widely separated from the coracoid, so 

 that some of the flat plate-like radials rest on the cleithrum. The scales 

 tend to disappear, or to be modified into spines embedded in the skin. 

 The myodome is present. 



Family Cottidae. The spinous dorsal is usually separate ; but the 

 scales and spines on the fins and head are less developed than in the 

 Scorpaenidae, as a rule. The eyes are generally placed high and close 

 together, the teeth small, the gills sometimes reduced to three and a half, 

 the anal spineless. The vertebrae may be numerous, especially in later 

 forms. 



Eocottus, A. S. W. ; Eocene, Italy. Lepidocottus, Sauv. ; Miocene 

 and Oligocene, Europe. Cottus, Art. (Fig. 474) ; Icelus, Kr. ; Jordania, 



