284 North American Species of Petromyzontidce. 



? Petromyzon lamotteni (Le Sueur, Mss.) DeKay, N. Y. Fauna, Fishes, 1842, 

 382, pi. 79, f. 249 (uo locality ; description insufficient ; possibly intended 



for A. branchialis. ) 

 Petromyzon maculos us Gronow, Cat. Fish. Ed. Gray, 1854, 2 ^Europe/. 



b. Land-locked form (unicolor). 



Ammocaetes unicolor DeKay, New York Fauna, Fishes, 1842, 383, pi. 79. 

 f. 25U (larva ; Lake Champlain). Gray, Cat. Chondr. Fish., 1851, 146. 



Ammoccetes fluviatilis Jordan, Ann. N. Y. Acad. Sci., 1877. 118 (Cayuga 

 Lake ; not Petromyzon fluviatilis L.). 



Petromyzon nigricans Jordan & Gilbert, Synopsis Fish. N. A., 1883, 11 (Ca- 

 yuga Lake). 



Petromyzon marinas dorsatus (Wilder, Mss.) Jordan & Gilbert, Syn Fish. N. 

 A., 1883, 869 (Cayuga Lake). Jordan, Cat. Fish. N. A., 1885, 4. 



Habitat. — Streams of North-eastern North America and of 

 Northern Europe, south to Chesapeake Bay. Ascending rivers 

 in the spring for the purpose of spawning, and thus land-locked 

 in lakes and streams of Western and Northern New York. 



The larva of this species is for a time blind, toothle.-s, and 

 with a contracted mouth, in which the lower lip forms a lobe 

 distinct from the upper. Later this lower lobe becomes conflu- 

 ent with the upper, and the eyes appear, while yet the mouth is 

 narrow and contracted. We have examined marine examples of 

 this species, and also numerous specimens in all stages of growth 

 from the larval to the adult form, collected by Dr. Burt G. 

 Wilder, in Cayuga Lake, at Ithaca, N. Y. Among these are 

 types of P. domains Wilder, which seems to be merely a land- 

 locked form not permanently distinct from P. marinus. 



The name unicolor is based on the larva of the land-locked 

 form, and it has priority over dorsatus. The characters assumed 

 to distinguish this form from the true marinus are, however, 

 more or less inconstant and not of specific value.* 



* The following are the characters assigned to P. marinus dorsatus (uni- 

 color) : 



" The Cayuga Lake Lamprey is apparently a distinct subspecies, differing 

 from P. marinus in the longer head (snout 1^ in chest ; head half longer than 

 chest ; in P. marinus, the snout is If in chest ; head one-third longer than 

 chest). Mandibulary teeth usually 8 or 9, Males with the back before dorsal 

 Jin compressed in a long hard fleshy ridge. Interspace between dorsals varia- 



