PBTEOMYZONTID^!. CXVI. 815 



2. P. nigricans, LeS. LAKGE BLACK LAMPREY. Head 

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

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

 distinctly separated; eyes and mouth very large; a de- 

 pression 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. (TPV&fer), and E.; properly a 

 marine species. (Several other Lampreys have been 

 described from our Eastern streams and coast, but they 

 are very doubtful.) 



3. P. niger, Raf. SMALL BLACK LAMPKEY. Head 

 moderate, longer than "chest," 8J in total length; depth 

 14; body scarcely compressed except behind; dorsal fins 

 rather high, slightly connected; eyes large; mouth rather 

 small, two rather large teeth well apart in front of oeso- 

 phagus; 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. 



2. ICHTHYOMYZON, Girard. LAMPERNS. 

 > Scolecosoma^ Grd. (JLarvce.) 



1. /. argenteus, (Kirt.) Grd. 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- 

 tinct in adult, concealed in young; mouth small, with 

 inconspicuous teeth; color ashy silvery, with numerous 



