LAMPETRA BROOK LAMPREYS 11 



Genus LAMPETRA Gray 



(brook lampreys) 



Supraoral plate crescent-shaped, with a large bluntish cusp at each 

 end, separated by a wide space, there being rarely a very small median 

 cusp ; lingual teeth small, with dentate edges, the median denticle en- 

 larged ; dorsal fin with a sharp notch or entirely divided. Small lampreys 

 of the brooks of Europe and North America. 



Fig. 10 



Oral disk of Brook Lamprey (Lpmpetra 



wilder i J. & E.) 



LAMPETRA WILDERI Jordan & Evermann 

 (brook lamprey; small black lamprey) 



Rafinesque, '20, Ichth. Oh., 84 (Petromyzon nigrum; name preoccupied); Jordan 



& Evermann, '96, B. U. S. N. M., 47, I, 13. 

 G., VIII, 504 (Petromyzon branchialis) ; J. & G., 9 (Ammocoetes niger); M. V., 10 



(A. branchialis); N., 52 (P. niger); J., 70 (A. niger); F., 86 (A. niger); L., 7. 



Length 6 to 10 inches; depth 13 to 16 in length; width of body 1.3 

 to 1.4 in its depth; distance from last gill-opening to front of dorsal 3.4 

 to 3.5 in length; last gill-opening to vent 1.9 to -2 ; muscular impressions 

 7.0-73. Color bluish black above, silvery below. Head (to first gill- 

 opening) 7.9 to 8.7 in length; diameter of expanded buccal disk less 

 than \ head; fimbria consisting of small and closely set tubercles, 

 not arranged in definite rows, and densest on lower lip; no flexible 

 lip inside fimbriae ; eye 6 to 7 in head; supraoral lamina with a large 

 triangular cusp at each end, separated by an interval nearly twice the 

 width of base of a single cusp ; intraorals 6 or 7 , a single cusp at each 



