CHONDROPTERYGII BRANCHIIS FIXIS. 297 



which is a Wind cavity. (1) The intestinal canal is straight 

 and thin, with a spiral valve. 



Petromyzon, Lin. (2) 



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

 the tail above and beneath is turned up into alongitudinal crest v^hich 

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

 visible fibres. 



Petromyzon, Dumer. 



The maxillary ring of the True Lamprey is armed with strong 

 teeth, and the interior disk of the lip, which is very circular, is fur- 

 nished with tubercles covered Avith an extremely hard shell, and 

 similar to teeth. This ring is suspended under 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 

 longitudinal rows of small teeth on the tongue, which moves back- 

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

 which distinguishes this animal. Water reaches the branchiae from 

 the mouth by a particular membranous canal, placed under the oeso- 

 phagus and perforated with holes, that may be compared to a tra- 

 chea. There is a dorsal before the anus and another behind it, 

 which unites with that of the tail. These fishes habitually fix them- 

 selves by suction to stones and other solid bodies; they attack the 

 largest fishes in the same way, and are finally enabled to pierce and 

 devour them. 



P. marinus, L.; BL, 77; the teeth better in Lacep. I, i, 2. 

 (The Sea-Lamprey.) Two or three feet in length, marbled 

 with brown on a yellowish ground; 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. Jluvialis, L.; Pricka; Sept-Oeil, &c.; Bl., 78, I. (The 

 River Lamprey.) From a foot to eighteen inches in length; sil- 



(1) Improperly styled a spiracle. With respect to this family in general, see 

 Dumeril, Diss, sur les Poiss., Cyclostomes. 



(2) Lampruye, Lampreda, Lamprey, corruptions of Lampetra, which is itself 

 modern, and, according to some, derived from Lambendo, petrus. Petromyzon is 

 the Greek translation of the same, by Artedi. It is somewhat singular that so 

 much uncertainty should envelope the ancient name of a fish so much esteemed, 

 and so common in the Mediterranean. 



Vol. IL— 2 N 



