THE FISHES OF OHIO., 



A. Body long and slender, eel-like ; skin smooth and slippery, wholly devoid of scales ; 

 no paired fins ; no lower jaw ; the mouth placed in or near the center of a large, 

 circular and sucker-like disc ; a single median nostril ; skeleton cartilaginous. — 



Class : Marsipobranchii (Cyclostomes). 

 AA. Body variously developed, scales usually but not always present ; paired fins pres- 

 ent ; lower jaw always present ; nostrils never median. — 



Class : Pisces (True Fishes). 



Class : MARSIPOBRANCHII. 



Order : HYPEROARTII. 

 Family: Petromyzonidae (Lampreys). 



Key to Genera. 



A. Sucker large, and furnished with numerous teeth which are in rows radiating from^ 

 the mouth ; horny plate above the mouth short and provided with 2 or 3 teeth, 

 which are placed close together. — Ichthyomyzon. 



AA. Sucker relatively small, and with few teeth ; mouth overhung with a crescent-- 

 shaped, horny plate, which terminates at each end in a distinct tooth; tongue 

 armed in front with a crescentic, serrated, horny plate. — Lampetea. 



Genus : Ichthyomyzon. 



Ichthyomyzon concolor (Kirtland). Silver Lamprey. 



Sucking disk large, moderately fringed ; teeth strong and nearly uni- 

 form ; two teeth on supraoral plate ; seven in the transverse row below 

 mouth, the remaining teeth arranged in about four concentric circles. Dorsal 

 fin arising midway from snout to end of tail, broadly notched, continuous, 

 with caudal ; anal fin also continuous with caudal. About fifty-two muscu- 

 lar grooves between gills and vent. General color bluish, sometimes, 

 blotched with black ; a dark blue spot above each gill opening. Length 

 about 12 inches. 



This species appears to be distributed throughout the state,, 

 though nowhere very common. It ascends small brooks in spring- 

 to breed. McCormick mentions finding females with ripe eggs 

 on May 22, in Vermillion river. The breeding date must be 

 considerably earlier in central Ohio, as Messrs. Parker, William- 

 son and the writer took young larvae a couple of inches long in 

 Big Jelloway creek, Knox County, during the latter part of May, 

 1898. On the same date a large larva seven inches long was 

 taken, so the species must continue in the larval stage something 



*It has been thought best to include here also the I«ampreys {Marsipobranchii) of 

 Ohio, for the reason that, in the popular idea, a lamprey is a " fish." 



