10 MARINE AND FISHERIES 



5 GEORGE v., A. 1915 



species is given by Forbes and Richardson ('08) for Illinois as 12 inches, and by 

 Jordan and Evermann ('96) as 10. Go Home specimens are probably immature, 

 none having been taken in the spring of the year. 



Oral disc always expanded. Supraoral tooth bicuspid; infraoral with 7 

 cusps (sometimes 4 or 6). There are 11 lateral, oblique, curved rows of unicuspid 

 teeth, of which 4 rows have their enlarged first cusps immediately lateral to the 

 mouth. Dorsal fin continuous, with a broad notch. 



For several years no specimens of the larva or Ammocoetes of this lamprey 

 were discovered, but in August, 1910, a single specimen was found in a decaying 

 submerged log at about the same place where all the metamorphosed specimens 

 were taken. The larva is 3^ inches in length, or approximately the size of the small- 

 est metamorphosed specimens. The dorsal fin is continuous, this character 

 differentiating the larva from that of the lake lamprey, the latter as described 

 by Gage ('93) having the dorsal fin divided as in the adult.' 



Petromyzon marinus unicolor, DeKay. 

 (Lake lamprey) 



This species is included provisionally. The dwarfed fresh water representative 

 of the marine lamprey {Petromyzon marinus), described by Jordan and Fordice 

 ('85), Meek ('85), and Gage ('93) occurs generally in the lakes of northern and 

 central New York. A lamprey, evidently representing the same variety occurs 

 abundantly in Lake Ontario, and is commonly taken by fishermen on whitefish 

 and lake trout. In this lamprey the dorsal fins are separate, the four extraoral 

 teeth bicuspid, the average length about 15 inches. 



Though there is no reliable information as to the occurrence of lake lampreys 

 in the upper lakes, and the whitefish and trout are practically free from lamprey 

 marks, fishermen state that lampreys of about 15 inches in length are sometimes 

 taken on whitefish and trout from deep water. This suggests that the lake lamprey 

 is present in small numbers, and perhaps accidentally. The silver lamprey does not 

 reach the size indicated, and up to the present has not been taken except in the 

 limited area represented by the running water of the falls of the river. Fishes such 

 as pike, on which the silver lamprey is commonly taken, are abundant elsewhere in 

 shore waters, but do not have lampreys on them. 



Family polyodontidae. 



Polyodon spathula, Walbaum. 



(Paddle-fish) 



Naturally an inhabitant of the Mississippi valley, but occasional specimens 

 taken in the Great Lakes. Noted here on account of two specimens reported by 

 Nash ( '08) taken near Georgian Bay waters, one at Sarnia*, the other at Spanish 

 River on the North Channel. 



* Vide, Prince E. E. Paddle-Nosed Sturgeon in Ontario. Ottawa Naturalist: Vol. XIII, 

 No. 7, 1899. 



