f 
Oh AEN \, 
THE NATURAL HISTORY SURVEY. 253 
Habitat: Same as costata. 
Remarks: This species is very rare. It may be distin- 
guished from costata by its smaller size, wider umbilicus, and 
by the last whorl being straight, while it is descending in cos- 
tata. It is extremely local, and the only specimens found 
were from one locality on the Du Page Feeder. It is by some 
considered a synonym of cosfata, but seems to be sufficiently 
distinct. 
SUBORDER BASOMMATOPHORA. 
“Tentacles flattened-triangular or subcylindrical, contrac- 
tile (but not invertible); eyes at their bases, sessile.” 
Shell usually covered by a corneous epidermis and oblong, 
few whorled, without operculum. Mostly aquatic or littoral.”* 
Superfamily Gehydrophila. 
“Teguments rugose; terrestrial, but usually inhabiting sea- 
shores” (or bodies of fresh water).* 
FAMILY AURICULID&. 
“Shell spiral, covered by an epidermis, solid, usually thick; 
spire more or less elevated; whorls sometimes flattened; aper- 
ture elongated, contracted by columella teeth, and often also 
by teeth within the lips.” 
“Lingual membrane broad and elongated; teeth numerous, 
in slightly bent cross-series; central tooth equilateral, narrow, 
tricuspid; lateral and marginal teeth also tricuspid, rather ine- 
quilateral, diminishing in size toward the outer edge. Head 
ending in a snout; mouth with a horny, lunate upper jaw, and 
with two dilated buccal lobes, united above, separate below; 
tentacles subcylindrical, contractile; eyes sessile at the inner 
sides of their bases. Mantle closed, with a thickened margin; 
respiratory orifice posterior, onthe right side. Sexes united.’* 
Animal frequenting salt marshes or fresh bodies of water 
(inland). 
Genus CARYCHIUM Miller, 1774. 
Shell; Thin, few whorled, pupiform; columella armed 
with a fold (sometimes absent); parietal wall armed with one or 
two denticles; peristome expanded, with a denticle on the in- 
side. 
*Tryon, Syst. and Struct. Conch., Vol. III, p. 9a. 
