THE NAUTILUS. 23 



occurring in Ohio as well as in the known Illinois localities, 

 Chicago, Joliet, and Grundy County. In a previous paper 

 (Journ. Geol., XXVIII, p. 448, 1920) it was listed as Amni- 

 cola lustrica variety, its differentiation having been suggested 

 by Dr. Pilsbry. It is so markedly different from lustrica as 

 found recently, and as represented in some marl deposits, 

 that a name seems very necessary. 



Three forms of Amnicola related to lustrica have come 

 under the writer's observation. The typical form, wide, with 

 moderately convex whorls and a large body whorl ; this is in 

 the collection of the Museum from Milwaukee, Wis. (30th 

 Street) ; a wide form like the type but with thickened lip and 

 solid shell; specimens of this form have been seen from 

 Randolph County, Indiana; and the form herein described, 

 which is narrower and more scalariform than the type. These 

 all represent, probably, different types of environments. The 

 likeness of gelida to Amnicola oneida Pilsbry, from Oneida 

 Lake, N. Y. (NAUTILUS, XXXI, p. 46, 1917) is striking, and 

 suggests that oneida may be the recent manifestation of the 

 fossil form. It will be remembered that the old Rome outlet, 

 in use for the discharge of the waters of the Great Lakes, was 

 by way of Oneida Lake, and western species had easy access 

 to this waterway. 



AMNICOLA LEIGHTONI Baker. 



This recently described Pleistocene Amnicola (NAUTILUS, 

 XXXIII, p. 125, 1920) also occurred in the Grundy County 

 material. The shells are more variable in Illinois than in the 

 type locality in Logan County, Ohio, the spire being long or 

 short and the body whorl varying greatly in obeseness. Con- 

 tinued study of this species in comparison with the Maine 

 species (ivinkleyi) lead the writer to consider the fossil form 

 as a distinct species, as indicated above. 



VALVATA TRICABINATA Say. 



This common species is most abundant in nearly all lacus- 

 trine and fluviatile deposits of the Pleistocene period. Like 

 the recent shells, it varies greatly in the carinate condition of 



