164 THE CHICAGO ACADEMY OF SCIENCES. 



Shell: Subglobose, rather solid, imperforate; surtace cov- 

 ered with numerous short, stiff hairs, beneath which may be 

 seen fine growth lines; nuclear whorl without hairs; color red- 

 dish-brown or chestnut; periphery subangulated; sutures very 

 deeply impressed; whorls five, rounded, slowly and regularly 

 increasing, the last deflected near the aperture and constricted 

 behind the peristome; spire a little elevated, convex; aperture 

 nearly closed by the thickened peristome and parietal tooth; 

 parietal tooth long and narrow, elevated, extending from the 

 center of the base of the shell into the aperture near the upper 

 part; peristome narrow, thickened, reflected against the whorl 

 with a small, well-marked notch near the center of the base 

 of the aperture; umbilicus covered and the region indented; 

 base of shell convex; within the base of the shell, situated be- 



FIG. 25. 



Jaw and radula of POLYGYRA HIRSUTA Say. (Original.) c, central 

 tooth; 1, first lateral; 12, intermediate tooth; 16, 20, marginal teeth; J, jaw. 



yond the line of sight, is a transverse tubercle, which starts 

 from the apex; this cannot be seen without breaking the whorls. 

 Greater diameter, 7.75; lesser, 7.00; height, 5.00 mill. (8451.) 

 8.30; " , 7.75; " 5.00 " (10438.) 

 9.00; " 8.00; " 5.00 " (12399.) 



Animal: With a long, narrow foot, truncated before, 

 pointed behind; head distinct, blackish or slate color, as well 

 as the tentacles and eye-peduncles; tentacles short, blunt; eye- 

 peduncles long, thick, cylindrical, -the eyes on enlargements 

 at their tips; the foot and a part of the body is semi-transpa- 

 rent; foot 13 mill, long and 2 mill. wide. Heart situated to 

 the left of the center of the parietal tooth, pulsations regular, 

 eighty per minute. 



Jaw: Similar to Polygyra monodon, but with eight stout 

 ribs (Fig. 25, J). 



