North American Species of PetromyzontidcB. ~^1 



Supraoral lamina bicuspid ; infraoral lamina with 7 to 9 cusps ; teeth 

 in obliquely transverse rows, 4 to 7 in each row ; the lateral teeth 

 on each side of mouth bicuspid, the other teeth simple ; head and 

 disk large ; dorsal tins low, well separated ; 64 muscular impres- 

 sions between gill-openings and vent ; back with an elevated fleshy 

 ridge anterior to dorsal fin (in males ?) in spring ; color bluish 

 brown, mottled with blackish confluent patches, rarely nearly plain, 

 dull brownish white below. Marinus, 4. 



2. PETKOMYZON CASTANEUS. 



Ichthyomyzon castaneus Girard, U. S. Pac. R. R. Surv., 1858, 381 (Galena, 



Minn). Gunther, Cat. Fish. Brit. Mus., VIII, 1870, 507 (copied) ; 



Bean, Proc. U. S. Nat. Mus., 1882, 117 (Forlorn Hope, Louisiana). 

 Petromyzon caslaneus Jordan & Gilbert, Synopsis Fish, N. A., 868, 1883 



(name only). Jordan. Cat. Fish. Waters N. A., 1885, 4. Cragin, 



Bull. Washburn Coll. Lab., Topeka, Kas., 1885, 99 (Mill Creek, 



Shawnee Co., Kas.). 

 ? Ichthyomyzon hirudo Girard, U. S. Pac. R. R. Surv., 1858, 382 (Fort Smith, 



Arkansas). Gunther, Cat. Fish. Brit. Mus., 1870, VIII, 507 (copied). 



Bean, Proc. U. S. Nat. Mus., 1882, 119 (original type^. 

 ? Ammoccetes hirudo Jordan, Man. Vert., Ed. 1, 1876, 350 (in part). 

 ? Petromyzon hirudo Jordan, Cat. Fish. N. A. , 1885, 4. 



Habitat. — Mississippi Valley. 



Of this species, only the above-named examples are known. 

 Thus far it appears to be distinct from P. concolor. 



The type of 7. hirudo has 7 teeth in the infraoral lamina, in- 

 stead of 9 as in the specimens referred to castaneus. The origin 

 of dorsal is said to be nearer tip of caudal than the tip of snout 

 in hirudo, while in castaneus it is nearly midway between these 

 two points. No second specimen properly referable to P. hirudo 

 has been found, and as the characters referred to are known to 

 be not very constant in this group, P. hirudo will probably be 

 found to be identical with P. castaneus. 



Since the above was written, we have seen an important " Note 

 on the Chestnut Lamprey," published by Prof. F. W. Cragin, 

 in the Bull. Washburn College Laboratory for March and April, 

 1885. Of four specimens of Petromyzon castaneus obtained by 

 him from the mouth of Mill Creek, Shawnee Co., Kansas, one 

 had eight mandibulary teeth, two nine, and one twelve. All 

 had the maxillary tooth tricuspid, and the color more yellowish 



