164 



backwards. The nioiitli is furnished with several rows of 

 teeth in both jaws, cuttini; and sharp, tlie points directed 

 outwards and backwards. All the upper part of the body is 

 of a slate color, which is deeper upon the head and lighter 

 beloAv the lateral line; beneath white. Mr. Storer mentions 

 a row of circular, white spots just under the anterior portion 

 of the lateral line, and a few similai- spots upon the back: 

 they are certainly a rare exception. Upper lobe of the caudal 

 flu broad, and as long again as the lower portion. T-engtli, 

 1 to 3 feet. 



Squalus amerlcunus, Grill. 



Acantliias aincricanus, Storer, Synopsis p. 500. 



Occasional near the moutji of Chesapeake Bay and in the 

 ocean adjacent. 



LXXI— PETROM l^ZONTIDiE. 



PlCrROMYZON. Artcdi. 



P. americanns, 



The American Sea-Lamprey or Lamprey-Esl. 



Bluish brown, mottled witli black olive-green, wliicli is 

 the general color along the back; beneath silvery grey; first 

 dorsal fin greenish; the second reddish: t;iil dark brown. 



Bod}' cylindrical anteriorly, compressed i>osteriorly, and 

 terminating in an acute tij); a slight keel upon the back. — 

 Head depressed, and wlien t!io moutli is closed, obtusely conic: 

 a singular tubular orifice erpiidistant from, and slightly an- 

 terior to the eyes. Mouth forming a longitudinal fissure. 

 and when attached to any object assumes the finm of a regu- 

 lar circle. Teeth of various kinds, wliich may be considered 

 as disposed in concentric circles about a common centre: in 

 the throat, and ])artly closing it, are three hirgo teeth. — 

 Length, 20 to 30 inches. 



Fin- rays:— D. 80. DO; 0. 80. 



— americanufi , Lesneur. Trans. Am. Phil. ^oe. i ]i, 383: 

 DeKay, New Yorii Fauna, Fishes, p. 379, pi. GG, fig. 210; 

 Storer, Mem. Am. Acad. IX, ]>. 251, pi. 28, fig. 4. 



Common in tlie lowci ;,-art of tue Potomac River, and even 

 found in the fresher waters of tliat river, beyond the reacli 

 of tide. Occasionally occurs in the Gunpowder and Back 

 Rivers. The young ones run long distances \\\^ our stony 

 creeks and branches niriiiy miles from brackish waters. 



Acad. Coij.. S. I. 



