STRUCTURE OP FISHES. 393 



small prickly or flattened spines. To the Ganoid belong the sturgeon, 

 lepidosteus, hassar-fish, and polypterus ; the fish of this order are more 

 generally found in a fossil state, and their scales are of a bony struc- 

 ture. To the Ctenoid belong the pike, perch, pope, basse, weaver-fish, 

 &c. ; their scales are notched like the teeth of a comb. To the Cycloid 

 belong the salmon, herring, eel, carp, blenny, and the majority of our 

 edible fishes; their scales are circular and laminated. The scales of the 

 eel tribe are of an oval figure, and are amongst the most remarkably 

 that can be selected for microscopic examination. To procure them, a 

 sharp knife must be passed underneath the epidermal layer, and a por- 

 tion of this raised, in the same manner as described for tearing off the 

 cuticle of plants : after some trials a few will be detached. They are of 

 an oval figure, rather softer than the scales of other fishes, and in some 

 parts of the skin do not form a continuous layer. When the skin has 

 been stripped off, previous to the fish being cooked, the scales may be 

 obtained from the under surface by tearing them away either with a 

 knife or pair of forceps. The scales of the viviparous blenny are of a 

 circular figure, and situated under the epidermal layer ; they have been 

 described by Mr. Yarrell as mucous glands, in consequence of their 

 figure and the smallness of their numbers. The surface of the skin of 

 this fish, when fresh, appears to be covered with follicles ; if, how- 

 ever, a portion be scraped 

 off, it will be seen to be a 

 mass of delicate circular 

 scales. A piece of the skin, 

 when dried, will exhibit the 

 scales to great advantage, 



and, like those of the eel, is a fig. 185. The Stickleback. 



beautiful object for polarised 



light. The colours of fishes are said to be due to the presence of fatty 

 matter in the skin; but the beautiful metallic tints displayed by so 

 many of them are produced by the numerous microscopic plates, or 

 scales, which are distributed over the surface of the true skin. 



It will interest our readers to know, that Mr. Lloyd, of 164 St. 

 John Street Koad, has taken steps to fit-up and stock marine and 

 fresh-water aquwtia with fish and appropriate plants, at very moderate 

 prices. 



