138 ORDER ACANTHOPTERYGII. 



min a ted by a long and strong spine, which forms a 

 powerful weapon. All their scales are carinated. 



The Mediterranean species (Trigla volitans, Lin., 

 Bl. 351.) is a foot long, brown above, reddish under- 

 neath ; the fins are black, spotted with blue. 



There is a similar species in the Indian seas (Dactyl. 

 orientaUs, Cuv., Russel 161.) 



Cephalacanthes, Lacep. 



Have nearly the same form, and particularly the same 

 head, as the Dactyloptera, from which they differ by 

 the total absence of the supernumerary fins or wings. 

 Only one species is known, which is very small, and 

 belongs to Guiana, and not to India, as has been 

 always said, (Gasterosteus spinarella, Lin. Mus. Ad. 

 Fred. pi. xxxii. f. 5.) 



Cottus, Lin. 



Have the head broad and depressed, shielded, and va- 

 riously armed with spines or tubercles ; two dorsal 

 fins; there are teeth on the front of the vomer, but not 

 on the palate; there are six rays to the gills, and three 

 or four only to the ventral fins. The lower rays of the 

 pectoral fins, as in the weavers (Trachiniis,L.), are not 

 ramified ; their ccecal appendices are not numerous, 

 and they are without an air-bladder. 



The species belonging to the fresh waters have the 

 head nearly smooth, and one spine only on the pre- 

 operculum ; their first dorsal fin is very low. The 

 most common species is 



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