PISCES— LAMPREY. 721 



fishery was but little attended to, it may be conjectured, that their age is 

 still more considerable. 



SUB-CLASS I. — CARTILAGINOUS FISHES. 



The bones of the fishes of this division are essentially cartilaginous, and, 

 in general, are never formed of bony fibres. The most general character 

 common to the cartilaginous fishes, and sufficient to distinguish them from 

 all others, is that of wanting entirely, or having only in a rudimentary form, 

 the maxillary and intermaxillary bones, the place of which is supplied by 

 bones analogous to the palatine ones. 



ORDER I. — CYCLOSTOMI. 



Fishes of this order have the jaw fixed in an immoveable ring ; bronchiae 

 fixed, and the openings numerous. 



THE LAMPREY A 



The lamprey much resembles the eel in its general appearance, but is of a 

 Jghter color, and rather a clumsier make. It differs, however, in the 

 mouth, which is round, and placed rather obliquely below the end of the 

 nose. It more resembles the mouth of a leech than an eel ; and the animal 

 has a hole on the top of the head, through which it spouts water, like the 

 cetacea. There are seven holes on each side for respiration ; and the 

 fins are formed rather by a lengthening out of the skin, than any set of 

 bones or spines for that purpose. As the mouth is formed resembling that 

 of a leech, so it has a property resembling that animal, of sticking close to, 

 and sucking any body it is applied to. It is extraordinary, the power they 

 have of adhering to stones ; which they do so firmly, as not to be drawn off 

 without some difficulty. We are told of one that weighed but three pounds 

 and yet it stuck so firmly to a stone of twelve pounds, that it remained 

 suspended at its mouth; from which it was separated with no small diffi- 

 culty. As to the intestines of the lamprey, it seems to have but one great 

 bowel, running from the mouth to the vent, narrow at both ends, and wide 

 in the middle. 



1 The genus Petromyzon has the maxillary ring armed with strong teeth ; lips formed 

 for suction ; tongue with two rows of small teeth; a dorsal fin before, and another behind 

 the anus. 



91 61 



