268 -A MANUAL OF AMERICAN LAND SHELLS. 



teeth. lu those species the superior tooth on the peristome is trans- 

 verse, compressed, and larger than the inferior one, from which it is 

 separated by a "remarkable sinus," distinctly visible on looking into 

 the aperture; the inferior tooth is obtuse. Immediately behind the 

 peristome the position of the teeth is marked by small shallow pits, 

 giving the character to the last whorl designated bj^ Shuttleworth 

 ^''scrohiculaio-constrictus,''^ and the striae run over the whorl up to the 

 peristome. In Hazardi the two teeth within the peristome are of the 

 same character as the superior one in fastigans and Troostiana ; the in- 

 ferior tooth is, however, the larger, and so partially conceals the lower 

 margin of the superior one as to obstruct the view into the aperture, 

 and give no appearance of separation " by a remarkable sinus." Both 

 the teeth are more deeply seated than in the other species. The 

 nature of the scrobiculation behind the peristome in Hazardi alone suffi- 

 ciently distinguishes it from its allies. The space behind the peristome, 

 and between it and the curved pit showing the seat of the superior 

 tooth, is convex and smooth, the striae not extending over it. 



This species has, .in common with fastigans and Troostiana, a thin, 

 brown, but more sparingly hirsute epidermis. I have noticed the 

 tubercle within the last whorl, near the aperture, in fastigans and 

 Troostiana, but no such process exists in the species now under con- 

 sideration. In Hazardi the inferior tooth of the peristome, at its inner 

 end, is continued back within the aperture, forming a white, erect 

 lamella on the floor of the whorl, parallel with and leaving a narrow 

 sinus between it and the inner wall, to which it is joined at its extrem- 

 ity, about two and a half millimeters from the edge of the peristome. 

 The i^osition of this lamella can be seen through the shell. 



Jaw as usual in the genus ; ribs numerous. 



Lingual membrane (Terr. Moll., Y, Plate VI, Fig. O) has 16-1-16 

 teeth, with 8 laterals. At least 3 of the transition teeth, or first mar- 

 ginals, have no bifurcation to the inner cutting point. Beyond these 

 the marginals have the point bifid. 



Genitalia unobserved. 



Polygyra Troostiana, Lea. 



Shell rimately umbilicated, discoidal, slightly convex above, flat- 

 tened below, obtusely carinated, with separated, strong, rib-like striae 

 throughout,* hirsute, russet horn-color; spire not much elevated ; whorls 



* Some, of the striiB exteud over the carina on to the base of the shell, without being 

 cjirriecl into the umbilicus. 



