INSTRUCTION. 9 



latter term on account of its suggestiveness ; d is the anal 

 fin, for which the writer can offer no English substitute ; 

 c are the two ventrals or belly fins ; b is the pectoral or 

 shoulder fin, having a complemental one on the other 

 side of the fish ; and a represents what in learned lan- 

 guage are called branchiostegous rays, a name that, 

 being translated, means merely gill-rays. What is not 

 in a name ! h is the lateral line. Then bearing in mind 

 the great divisions of soft and hard finned, the subdi- 

 visions are distinguished by the fish having the ventrals 

 behind the pectorals and on the abdomen, giving them 

 the name of abdominal fish, or before the pectorals, 

 giving rise to the name jugular or throat finned, and 

 below the pectorals, giving the name thoracic or shoulder- 

 finned fish. Philosophers pay little attention to the 

 dorsal and anal fins, and fish, without losing their iden- 

 tity, can have as many as they please. In caudals, 

 unlike human Caudles, they are restricted to one. There 

 are other fish, such as eels, denominated apodal ov footless, 

 because the lower fins or feet are wholly wanting. 



After having examined the texture, number and loca- 

 tion of the fins, and counted the number of the rays in 

 each, the naturalist next turns his attention to the hard 

 bony portion of the head, which covers the gills, and opens 

 and shuts as the fish breathes, and which, with the excel- 

 lent common sense for which naturalists are notorious, 

 he calls the operculum. It is divided into the operculum, 

 or gill-cover proper, No. 1 ; the jpre-operculum, or fore 

 gill-cover, No. 2 ; the inter-oj>ercul/wm, or middle gill- 

 cover, No. 3 ; and the sub-operculum, or under gill-cover, 

 No. 4. The head, in the foregoing diagram, is intended 



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