PETEOMYZONTED^E. CXVI. 349 



2. AMMOC(ETES, Dumeril. LAMPERNS. 



Lampetra, Gray. 



>AmmocceteS) Dumeril, (Z/arvce.) 



Ichthyomyzon & Scolecosoma, Grd. 



1. A.fluv/at/'//s,(L.)Jor. LARGE BLACK LAMPREY. Head 

 very large, longer than the "chest," 6 in length; depth 

 about 13; body little compressed; dorsal fins rather low, 

 distinctly separated; eyes and mouth very large; a 

 depression between eyes and snout; a single bicuspid 

 tooth in front of oesophagus; mandibulary plate curved, 

 with about eight pointed teeth; rest of mouth covered 

 with rather large teeth disposed in oblique cross-rows, 

 five or more in each row; lips fringed; L. 12. Lakes 

 and streams, Cayuga L., N. Y. (Wilder), and E.; prop- 

 erly a marine species. Also in Europe. (P. nigricans, 

 LeS., the American form.) (Several other Lampreys 

 have been described from our Eastern streams and coast, 

 but they are very doubtful.) 



2. A. niger, (Raf.) Jor. SMALL BLACK LAMPREY. Head 

 moderate, longer than "chest," &J in total length; depth 

 14; body scarcely compressed except behind; dorsal fins 

 rather high, slightly connected; eyes large; mouth rather 

 small, one tooth with two cusps well apart in front of 

 oesophagus; mandibulary plate nearly straight, with about 

 eight sub-equal teeth; a few scattering teeth on sides of 

 mouth; snout rounded; dark blue black, unspotted, sil- 

 very below; L. 8 to 11. Great Lakes, Upper Miss, and 

 Ohio Valley, abundant in many localities, ascending 

 small brooks in the spring. 



3. A. argenteus, (Kirt.) Jor. SILVERY LAMPREY. Head 

 quite small, shorter than " chest," about 10 in length; 

 depth nearly the same, in adult; body stout, compressed; 

 dorsal fin very high, with a shallow depression; eyes dis- 



