^ nSHES. 



Petromyzon,* Lin. 

 The Lampreys have seven branchial openings on each side ; the skin 

 of the tail above and beneath is turned up into a longitudinal crest 

 which supplies the place of a fin, but in which the rays resemble 

 scarcely visible fibres. 



Petromyzox, Diimer. 



The maxillary ring of the True Lamprey is armed with strong 

 teeth, and the interior disk of the lip, Avhich is ver\' circular, is fur- 

 nished with tubercles covered with an extremely hard shell, and simi- 

 lar to teeth. This ring is suspended imder a transverse plate which 

 appears to supply the want of intermaxillaries, and on the sides of 

 which vestiges of maxillaries may be observed. There are two lon- 

 gitudinal rows of small teeth on the tongue, which moves backwards 

 and forwards like a piston ; by this, that suction is produced which 

 distinguishes the animal. Water reaches the branchiae from the 

 mouth by a particular membranous canal, placed under the oesophagus 

 and perforated with holes, that may be compared to a trachea. There 

 is a dorsal before the anxis and another behind it, which unites with 

 that of the tail. These fishes habitually fix themselves by suction to 

 stones and other solid bodies; they attack the largest fishes in the 

 same way, and are finally able to pierce and devour them. 



P. viarlnus, L. ; Bl., 77 ; the teeth better in Lacep. I, i, 2. (The 

 Greater or Sea Lamprey.) Two or three feet in length, mar- 

 bled with brown on a yellowish groimd ; first dorsal very distinct 

 from the second ; two large approximated teeth on the upper 

 part of the maxillary ring. It ascends the mouths of rivers in 

 the spring, and is highly esteemed. 



P. fluviaUs,L,; Prlcka; Sept-Oeil, &c. ; BL, 78, 1. (The 

 Lesser or River- Lamprey.) From a foot to eighteen inches in 

 length ; silvery, blackish and olive on the back ; first dorsal very 

 distinct from the second ; two large separated teeth on the max- 

 illary ring. Lihabits rivers, &c. 



P. planeri, Bl. ; Sucet, &c. ; Gesner, 705. (Small River Lam- 

 prey.) From eight to ten inches long ; teeth and colours of the 

 fluvialis ; the two dorsal contiguous or united. Rivei's, &c.(f ) 



Myxine, Lin. 

 But a single tooth on the upper part of the maxillary ring, which is 



* Lamproye Lampreda, Lamprey, con-uptions of Lampefra, which is itself modern, 

 and, according to some, derived from Lambendo, petras. Pefromyzon is the Greek 

 translation of the same, by Artedi. It is somewhat singular that so much uncer- 

 tainty should envelope the ancient name of a fish so much esteemed, and so common 

 in the Mediterranean. 



t N.B. The figure of the Planeri, Bl., 78, 3, is a young J! la-ial is. I also think 

 ihztthe Petrom. sucet, Lacep., II, 1, 3; — sept-oeil, IV, xv, 1 ; — Noir, lb., 2, are mere 

 varieties of the planeri: but the fig. I, ii, 1, under the name of Lamproyon, Petrom. 

 branchialis, represents a peculiar species of this genus, and not an Ammocoetes. I 

 SM no differexice betweeathe Petrom. arc/entetis, Bl., 415, 2, and the fluaalis. 



