FISHES OF NEW YORK 15 



Ichtlujomi/zon argenteus Jordan & Gilbebt, Bull. 16, U. S. Nat. Mus. 10, 



1882. 

 Ichthyomyzon concolm- Jordan »& Evermastn, Bull. 47, IT. S. Nat. Mus. 11, 



1896. 



The silver lamprev belongs to the subgenus Ichthyomy- 

 z n of Girard. The tooth on the front of the tongue is divided 

 in two parts by a median groove and the dorsal fin is continu- 

 ous but deeply notched. The maxillary tooth is bicuspid; 

 the teeth on the disk are in about four series and all small. 

 The tooth-bearing bone of the lower part of the mouth has 

 seven cusps. The head (from tip of disk to first gill opening) 

 is two fifteenths of the total length; with the gill openings its 

 length is contained four and three fourths times in the totaL 

 There are 51 muscular impressions from gills to vent. The 

 body is rather stout, compressed posteriorly. The head is broad 

 and the buccal disk large with its edges not conspicuously 

 fringed. Color bluish silvery, sometimes with blackish mott- 

 lings. Above each gill opening there is a small bluish blotch. 



The silver lamprey or mud eel is found in the Great lakes 

 region and the Ohio and Mississippi valleys. It grows to a 

 length of 12 inches and is usually found in deep water, but runs 

 up the small streams to spawn in the spring. It is a trouble- 

 some parasite on the lake sturgeon, the paddleflsh, yellow 

 perch and some other species. It becomes fixed to the skin by 

 means of its suctorial disk and the irritation of its teeth some- 

 times causes deep ulcers at the point of attachment. This 

 lamprey has the same peculiarities of development as the sea 

 lamprey and sometimes remains in the larval condition, blind 

 and toothless, till it has reached a length of 8 inches. 



Genus lampetra Gray 



Small lampreys inhabiting brooks of Europe and North Amer- 

 ica. The dorsal fin either notched or divided into two parts, 

 the posterior part continuous with the anal around the tail; 

 supraoral lamina broad, crescentic, with a large obtuse cusp 

 at each end and sometimes a minute median cusp; lingual teeth 

 small, with a crescentic toothed edge, the median denticle en- 



