12 FISHES OF ILLINOIS 



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

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

 rather weakly developed.* Dorsal fin consisting of an anterior and 

 posterior portion, separated in adults by a deep notch (in breeding sea- 

 son) or divided by a narrow space; in larvas the fin divided by a space 

 i [ual to the greatest height of the fin; first dorsal about half the height 

 of second. 



Males with a long urogenital papilla, whose length in breeding season 

 is equal to the diameter of the eye. 



Here described from 5 specimens, one from Lake Michigan 

 (presented by Dr. Jordan), and four from Cayuga Lake, New York 

 (from Dr. Gage). A half dozen larvae received from an unknown 

 source in the winter of 1903, probably from within Illinois and in 

 answer to circular letters of inquiry concerning lampreys, are 

 doubtless of this species. Its almost total absence from our col- 

 lections is probably a consequence of its small size and non-para- 

 sitic habit. 



This species is known from western New York and the Great 

 Lakes to the Ohio and Mississippi rivers and west to Iowa and 

 Kansas. 



* It is the belief of Gage ('93) and others that this lamprey is not parasitic in 

 habit. 



