Storey's Synopsis of the Fishes of North America. 265 

 ORDER III. CYCLOSTOMI. 



Gills purse-shaped, fixed, opening outwards by several apertures. Jaw- 

 represented by an immovable cartilaginous ring, formed by the union of the 

 palatine and mandibular bones. Intestinal canal straight and narrow. 



FAMILY XXXV. PKTROMYZONIDJE. 



Body elongated, cylindrical, eel-shaped. No pectorals nor ventrals. Fins 

 without rays. 



GENUS I. PETROMYZON, Lin. 



Seven branchial apertures on each side of the neck. Maxillary ring armed 

 with strong teeth. Mouth beneath. 



1. Petromyzon Americanus, Lesueur. 



Body cylindrical anteriorly, compressed posteriorly, and terminating in an acute tip. A 

 slight keel upon the back. Above olive-brown, mottled with dark-brown, almost black, con- 

 fluent patches ; beneath of a uniform dull brown. Three large teeth in the throat. 



Length, 20 to 30 inches. 



Massachusetts, Storer. Connecticut, Linsley. New York, Mitchill, Dekay. 



Petromyzon marinus, Great Lamprey, Mitchill, Trans. Lit.'and Phil. Soc. of N V., i. p. 4GI. 

 Petromyzon Americanus, Lesubdk, Trans. Amer. Phil. Soc. (N< sv Series), 1. p. 3S2. 

 " " Hist. N. A. Fishes, inert., plate. 



" American Lamprey, Ptorer's Report, p. 195. 



American Sea-Lamprey, Dekay's Report, p. 379, pi. &Q, fig. 216. 



2. Petromyzon nigricans, Lesueur. 



Body above of a deep blue color ; beneath bluish white. Mouth with numerous incurved 

 teeth, or bony spines, projecting from widened bases, resembling the spines with which the 

 Raiae are armed. Dorsals white. Caudal triangular at its termination. 



Length, 6 to 7 inches. 



Massachusetts, Lesueur, Storer. Connecticut, Linsley. 



Petromyzon nigricans, LBsmjCR, Trans. Amer. Phil. Soc. (New Series), i. p. 3S5. 

 " Bluish Lamprey, Stoker's Report, p 197. 



" Bluish Sea-Lamprey, Dekai : Report, p -I, pi. 79, fig. 2-17. 



3. Petromyzon Lamottenii, Lesueur. 



Yellowish on the sides, with irregular patches of dark brown above ; white beneath. The 

 mouth pectinated on its margin- Dorsals continuous. 



77 



