THE NATURAL HISTORY SURVEY. 143 



B. Aperture with well-developed teeth. 



a. Parietal wall with one, peristome with two teeth. 



1. Perforate. 

 *Spire depressed, parietal tooth depressed, curved, 



thin tridentata 



**Spire rather elevated, parietal tooth elevated, almost 



straight, thick fraudulenta 



2. Imperforate inflecta 



b. A single large tooth on the parietal wall. 



1. Imperforate; peristome notched and continuous with 



parietal tooth hirsuta 



2. Perforate to imperforate; peristome simple, not contin- 



uous with parietal tooth monodon 



SECTION TRIODOPSIS Rafinesque. 



"Shell: Varying from depressed to globose-conoidal, um- 

 bilicate or imperforate; surface generally striated; whorls five 

 to six,, the last wider, more or less deflexed in front. Aperture 

 lunate, typically obstructed by three teeth, two on the lip, one 

 on the parietal wall; but any or all of the teeth often absent." 

 (Pilsbry, 1. c., p. 74-) 



51. Polygyra inflecta Say, pi. xxx, fig. 5. 



Helix inflecta SAY. Journ., Phil. Acad., Vol. II, p. 153, 1821. 



Helix clausa FERUSSAC. Tab. Syst., p. 38, No. 104; Hist., pi. xlix, fig. 2. 



Shell: Depressed, solid, imperforate; surface covered with 

 coarse striae, the spaces between the striae being twice or three 

 times the width of the striae, and the shell with numerous hair- 

 like projections scattered over the surface; apical whorls 

 minutely striate; periphery subangulated; sutures impressed; 

 whorls five, convex, rather closely coiled, the last whorl consid- 

 erably constricted behind the reflected peristome, so that the 

 edge of the reflected lip is on a level with the body-whorl; 

 spire very much depressed, slightly convex; aperture con- 

 tracted, armed with three teeth; the tooth on the outer lip is 

 tubercular and situated just below the periphery, a little deep- 

 seated; the tooth on the basal lip is also tubercular, and placed 

 at about the center, not deep-seated; the points of both teeth 

 point inward, and there is a marked circular sinus between 

 them; the parietal tooth is long, white, narrow, curved, elevated, 

 begins at about the center of the parietal wall, and extends in 

 an oblique direction until it meets the reflected peristome and 

 the umbilical region; peristome thick, white, reflected; umbili- 

 cus closed, but the region indented; base of shell flat-convex. 

 Greater diameter 11.00; lesser, 10.00; height, 6.00 mill. (8446). 



