476 FISHES. 



dredged at a depth of 360 fathoms off the coast of West 

 Africa; the latter genus possesses two gills only. Another 

 genus, covered with large scattered tubercles, Aegmonichthys, 

 has recently been described from JSTew Zealand. 



Thieteenth Family — Cottid^. 



Form of the hody oblong, sub-cylindrical. Cleft of the 

 mouth lateral. Dentition feeble, generally in villiform bands. 

 Some bones of the liead are armed ; and a bony stay connects 

 the p'oeopercular spine ivith the infraorbital ring. Two dorsal 

 fins {rarely one), the spinous being less developed than the soft 

 and than the anal. Ventrals thoracic, with five or less soft 

 rays. 



The fishes of this family are of small size, bad swimmers, 

 and generally living on the bottom, near the coasts, of almost 

 all the arctic, temperate, and tropical seas. Only a few live 

 in fresh water. They prefer shallow to deep water ; and there 

 is only one instance known of a member of this family living 

 at a great depth, viz. Cottus bathybius from the Japanese sea, 

 which is stated to have been dredged in a depth of 565 

 fathoms. Fossil representatives are few in number : two or 

 three species of Trigla ; others, although having a general 

 resemblance to the genus Cottus, were covered with ctenoid 

 scales, and therefore are referred to a distinct genus, Lepido- 

 cottus ; they are from tertiary formations. 



Cottus. — Head broad, depressed, rounded in front ; body sub- 

 cylindrical, compressed posteriorly. Scaleless; lateral line pre- 

 sent. Pectoral rounded, with some or all the rays simple. Jaws 

 and vomer with villiform teeth ; palatine teeth none. 



The "Bull-heads" or "Mdler's Thumbs" are small fishes 

 from the shores and fresh waters of the northern temperate 

 zone. Some forty species are known ; the greater number 



