10 L'YCLOSTOMl : IIVPEUOAUTIA. — III. 



Order III. UYPEIJOAUTIA. 



Characters j^ivcn above. Oin; family only, {vntpun, palate ; 

 apTios, cumj)letc.) 



Family 111. PETROMYZONTID^. (The L.amikkys.) 



IJiuly eel-^li:i|)i'(l, naktil, comi)resse(l behind ; month siibcircular, 

 aninii with horny teeth, which rest on papilla* ; gill openings 7, 

 arranged in a row along the side of the " chest " ; lips present, 

 fringed ; nostril on top of bead, just in front of eyes ; dorsal fin 

 more or less notched ; intestine with a spiral valve ; eggs small. 

 The lampreys undergo a metamorphosis, the larva of all species 

 being toothless and having the eyes rudimentary. The name 

 Ammocoetes was formerly applied to the larval forms ; originally, 

 however, to that of .1. hranc/iialis. (Jenera 3 or 4, species about 

 15, chiefly of the fresh waters of temperate regions. They attach 

 themselves to fishes, and feed by scraping off the flesh with their 

 rasihlike teeth. 



a. Second dorsal joined to the caud.il. 



b. Supraroral lamina (" ninxillary tooth ") expanded laterally, forminK a 

 crescent-sliapid plate, with a cusp at each end, and sometimes a median 



cusp; anterior lingual teeth hierrate Ammooktes, 3. 



66. Supraoral lamina contracted, of two or three teeth close together; discal 

 teeth numerous, in concentric series; buccal dii>k large (in adult, 

 very small in larva) rKTitoMvzoN, 4. 



3. AMMOCCETES Dumeril. (ufifxot, sand; Koirrj. bed.) 



a. Supraoral lamina with a very small median cusp or none; edge of anterior 

 lingual tooth small, crescent-sha|)ed, dentate, the median denticle en- 

 larged; buccal disk small, with few teeth. (Ammococtes.) 



3. A. branchialis (L.). Mru Lamprey. Brook LAMniEY. 

 Dorsal continuous, deeply notched, both parts high; about 3 

 bicus|)id teeth on each side of buccal disk ; the other teeth sim- 

 ple ; infraoral jilate with o to 'J blunt subctjual cusps ; head with 

 gills 4^ ; niyocommas t> 7, between gills and vent ; an anal papilla 

 present in spring. Color bluish black. L. 8. Cayuga L. (MuL) 

 to .Minn, and Ky , ascending brooks in spring, (/i") (1*. "iyctf 

 Kaf., not of Lacepede.) (Lat., having gills.) 



4. PETROMYZON (.\rtedi) Linnaeus. (nirfM, stone; 



^i/'^w, to suck.) 



a. Anterior lingual tooth divided in two by a median groove ; dorsal fin con- 

 tinuous, with a broad notch. {Ichthyomyzon Girard.) 



4. P. castaneus (fJirard). Supraoral lamina (maxillary tooth) 

 tricuspid ; ^(Jme lateral teeth bicusjiid ; infraoral lamina (mandib- 



