10 FISHES OF ILLINOIS 



instances of as many as 6 or 7 biscupid extraorals having been noted in 

 specimens with bicuspid supraorals.* 



Supraorals. Infraorals. Extraorals. Specimens. 



bicuspid 7 all unicuspid (concolor) 5 



7 1-7 bicuspid 5 



8 " 3 



8 2-7 " 6 



9 " 4 



9 6 " 



10 2 " 



unicuspid 7 " 



tricuspid 8 



8 3 



9 3 



10 6 



quadricuspid 13 8 



Dorsal fin continuous with caudal, with a perceptible depression in 

 front of vent ; greatest height of fin about ^ distance from vent to end of 

 tail, height at depression about | greatest height anterior to it, and 

 about ^ to § height of posterior portion ; the larvae with the dorsal fin 

 single as in adults. 



Our 15 collections of this species are chiefly from the Illinois 

 River at Havana, ^leredosia, Ottawa, and Pekin. We have also 1 

 collection from Green River, 1 from the Wabash at Mt. Carmel, and 

 several specimens from the Mississippi at Alton, and have records 

 of the occurrence of the species at Galena, Cairo, and Quincy. It 

 seems that lampreys are, on the whole, rather rare in our waters. 

 Illinois River fishermen seem to know little of them. Fishes with 

 lampreys attached, or with marks of their previous presence, are 

 not common in the seine catches along the Illinois. At Alton they 

 seem to be more numerous, showing their usual preference for 

 spoonbills, which species is said rarely to be taken at Alton cr 

 Grafton without lamprey marks. At Havana also they are com- 

 monest on the spoonbills — sometimes tw^o or three fast to a single 

 fish — and next on bufTalo-fish and carp. 



At Galena and at Cairo lampreys have been seen by one of the 

 State Laboratory assistants, Air. J. E. Hallinen, attached to large 

 catfish. We may consequently say that, so far as knowm to us, 

 lampreys are not seriously injurious to the fisheries or the fish popu- 

 lation of this state, perhaps because of the scarcity of suitable 

 nesting places in our comparatively sluggish and muddy streams. 



This species is found in the Great Lakes and the St. LawTence 

 River, in the valleys of the Ohio, the Missouri, and the upper Mis- 

 sissippi, and northward to the Assiniboin {castaneus). 



* A study of our 31 specimens of Ichthyomyzon shows an amount of intergrada- 

 tion in dental characters that makes impossible the separation of the nominal 

 species castaneus { = concolor), as is evident from the following tabulation: 



