348 LAMPKEYS. 



ORDER GGL-HYPEROARTIA. 



(The Lampreys.) 



FAMILY CXVL PETROMYZONTID^E. 



(The Lampreys.) 



Body eel-shaped, naked; dorsal and anal fins long and 

 low, usually continuous with the caudal; mouth suctorial, 

 armed with horny teeth which rest on papillae. Eggs 

 small. 



These animals undergo a metamorphosis; the young 

 are usually toothless, and have the eyes rudimentary. 

 Genera five or six, in temperate regions, found in all 

 waters. They attach themselves to fishes and other ani- 

 mals, and feed by scraping off the flesh, by means of 

 their rasp-like teeth. 



The American species are still very imperfectly known. 

 Until quite recently the larvte were considered as form- 

 ing distinct genera, which have been termed Ammoccetes, 

 Scolecosoma, Chilopterus, etc. 



* Maxillary teeth close together, not forming a crcscentic plate, 

 f Dorsals well separated. . . . PETROMTZON, 1. 



ff Dorsals connected ICHTHYOMYZOX, 2. 



** Maxillary tooth forming a crescentic plate, with a cusp at each 

 end ; dorsal continuous AMMOCOZTES, 3. 



/. PETROMYZON, Linnagus. LAMPKEYS. 



1. P. marinus, L. GREAT SEA LAMPREY. Resembles 

 the next, but larger, with a shorter head, which is but 

 little longer than the "chest" (space occupied by the 

 branchial openings); color olive brown, mottled with 

 black; L. 30 to 40. Marine, ascending rivers, eastward. 

 (P. (imericanus, LeS.) 



