522 



MICHIGAN SURVEY, 1905. 



Suborder BASOMMATOPHORA. 



Superfamily GEHYDROPHILA. 



Tentacles contractile, subcylindrical. E3^es sessile at the inner sides of 

 the bases. Operculum wanting. Genital orifices separated but on the same 

 side. Tegument rugose as in the Stylommatophom. 



Family AURICULID^. 



Shell spiral, covered with a heavy epidermis; aperture elongate or ovab 

 with strong folds on the columella; outer lip often dentate. Internal septa 

 usually absorbed. 



Head ending in a snout; mouth with a heavy lunate jaw, and with two 

 dilated buccal lobes, united above, separated below; tentacles cylindrical,, 

 contractile; eyes sessile at the under sides of the bases. Mantle closed, 

 with a thickened margin; foot long, posteriorly blunt; respiratory orifice 

 posterior on the right side, excretory orifice near it. Sexes united, orifices 

 of generative organs distant, on the right side. 



Genus CARYCHIUM Muller. 



Shell pupseform, very thin, transparent, with but few whorls; aperture 

 sub-oval, with one dentiform columellar fold, sometimes 

 obsolete; parietal wall with one or two teeth; peristome ex- 

 panded; extremities united by a parietal callus, the right 

 hand one with one internal tooth. 

 Fig. 163. Animal of Teutaclcs relatively large, cyhndrical, obtuse, eyes sit- 

 c. exiguum. (Binney.) uated below and behind the tentacles near their base ; foot 

 thick, obtuse behind, not transversely divided beneath. 

 (^^^^^^ Jaw slightly arched, without ribs or marginal denticulations, 



broadly striated towards the margin. 

 ^'^Irychium.''^ Teeth in slightly bent cross series; centrals equilateral, nar- 

 (Moquin-Tandon.) row; laterals broad, short, denticulated. 



Fig. 166. C. exiguum (Clapp.)" x20. 



Fig. 165. Dentition of C. exiguum. (Binney.) 

 CARYCHIUM EXIGUUM (Say). 



Shell minute, perforate, cylindrical, apex 

 obtuse, white, translucent, shining; whorls 4^, 

 regularly convex, nearly smooth, the last two 

 of about equal diameter; suture impressed; 

 aperture obliquely oval, decidedly more than 

 one-third the total altitude; outer lip reflected, 

 sinuous, moderately thickened, very strongly 

 arcuate at the upper outer portion; columellar 

 margin having an obtuse fold below and a 

 prominent entering fold above. 



Alt. 1.75-2.15, diam. .75-. 85 mm. 



