BULL-HEADS AND GURNARDS. 



38i 



appendages, and the pelvic pair have not more than five rays. The body may be 

 either naked, scaled, or protected by a single row of plate-like scales. The 

 members of this family, which are arranged under a good many generic heads, 

 are distributed over almost all seas, while a few inhabit fresh waters. Of com- 

 paratively small or medium size, these fishes have but poorly developed swimming 

 powers, and spend their time swimming or crawling at the bottom of the sea in 

 shallow water at no great distance from the coast. A Japanese bull-head is stated, 

 however, to have been dredged in five hundred fathoms of water. In a fossil state 

 gurnards referable to the existing genus occur in many of the European Tertiary 

 rocks ; while remains of bull-heads are met with in the upper Miocene of Basle, 



Bull-Heads. 



COMMON BULL-HEADS (liat. size.) 



and those of the allied extinct genus (Lepidocottus), distinguished by its ctenoid 

 scales, in the upper Eocene of Switzerland. 



The familiar bull-head or miller's thumb (Cottus gobio), of the 

 streams of Britain and many other parts of Europe, belongs to a 

 genus containing some forty species, mostly distributed over the fresh waters and 

 coasts of the temperate zone of the Northern Hemisphere. All are of small size, 

 and characterised by the broad, depressed, and rounded head ; the subcylindrical 

 body, somewhat compressed posteriorly ; the absence of scales ; the distinct lateral 

 line ; and the rounded pectoral fins, in which some or all of the rays are simple. 

 Villiform teeth are present on the jaws and vomer, although there are none on 

 the palatine bones. In the majority of the fresh-water species the spine on the 



