North American Helicidce. 293 



shallow pits, giving the character to the last whorl designated 

 by Shuttle worth " scrdbiculato-constrictus" — the striae run over 

 the whorl up to the peristome. In H. Hasardi, the two teeth 

 on the peristome are of the same character as the superior one 

 in fatigiata and Troosiiana, — the inferior tooth is however the 

 largest, and so partially conceals the lower margin of the supe- 

 rior 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 H. 

 Hasardi alone sufficiently 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 strise not extending over it. This character, 

 as well as the form of the parietal and other teeth, is shown in 

 Plate IX. fig. 27, 28. 



This species has, in common with fatigiata Say and Troos- 

 tiana Lea, a thin, brown, but more sparingly hirsute epidermis. 

 I have noticed the tubercle within the last whorl, near the 

 aperture, in fatigiata and Troosiiana, but no such process 

 exists in the species now under consideration. In H. Hazardi, 

 the inferior tooth of the labrum, 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 

 extremity, about 2^ mill, from the edge of the peristome. The 

 position of this lamella can be seen through the shell. 



In my remarks on H. fatigiata I have referred to the cha- 

 racter of the parietal tooth in this species. 



The size of my specimens is constant, viz., Diani., maj. 7, 

 min. 6, alt. 3 mill. 



In the Cabinet of the Academy at Philadelphia there are 

 three specimens (dead shells), labelled H. plicata Say, and 

 with memorandum on the label that they were deposited by 

 Say. The habitat given is Kentucky. These specimens agree 



