LAMPETRA — BROOK LAMPREYS 



11 



Genus LAMPETRA Gray 



BROOK LAMPREYS 



Supraoral plate crescent-shaped, with a large blimtish 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 enlarged; 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 {Lampeira wilderi 

 Gage) 



LAMPETRA WILDERI Gage 



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 

 1.4Tin 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 70-73. 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 }4, head; fimbrise con- 

 sisting of small and closely set tubercles, not arranged in definite rows, and 

 densest on lower Hp; no flexible lip inside fimbrise; 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; infraorals 6 or 7, a single cusp at each 

 end of the plate larger than those (4 or 5) between; 3 lateral (extraoral) bi- 

 cuspids on each side of mouth; remaining teeth simple, unicuspid, and rather 



