PETKOMYZONTLtLE. CXVI. 815 



2. P. nigricans, LeS. LARGE BLACK LAMPEEY. Head 

 very large, longer than the &quot; chest,&quot; 6^ 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. (Wilder), 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 LAMPEET. Head 

 moderate, longer than &quot;chest,&quot; 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. LAMEEKBTS. 



&amp;gt; Scolecosoma, Grd. (Larvce.) 



1. I. argenteus, (Kirt.) Grd. SILVEEY LAMPEEY. Head 

 quite small, shorter than &quot;chest,&quot; 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 



