158 AGARDHIA. 



A. armata, A. biarmata or A. macrodonta. There are 16 rib- 

 striae iu 1 mm. on the face of last whorl. These appear slightly- 

 less oblique than in A. macrodonta. The aperture has a mod- 

 erately developed columellar lamella, not emerging quite to 

 the peristome, and a well-developed subcolumellar. The lip- 

 tooth projects more than that of biarmata, but it is rather 

 slender, not massive as in macrodonta. The summit is hemi- 

 spherical, and the diameter is about equal in the last 5 whorls. 



Other specimens are shorter, of 7 whorls. The aperture 

 either as described above, or it has three lamella? on the 

 columella and an accessory lamella on the parietal wall near 

 the left angle. The general shape differs perceptibly, as the 

 spire tapers a trifle upward. Length 4.2, diam. 1.5 mm. ; 14 

 rib-stria? in 1 mm. on face of the last whorl (pi. 18, fig. 7). 



In still another form there may be only a small subcolu- 

 mellar lamella on the columella (pi. 18, fig. 11), or it may 

 lack lamella? completely (pi. 18, fig. 10). In either case, a 

 more or less deeply immersed columellar lamella is visible in 

 an oblique view in the mouth. 



10. Agardhia lamellata (Clessin). PI. 18, figs. 13, 14. 



Having a lamella on the parietal wall considerably length- 

 ened inward, with a fold in the left upper angle of the mouth, 

 with a denticle on the left side of the basal margin (in the 

 corner below the columellar plate), and with a tooth-like ; 

 thickened impression of the outer margin (Bielz). 



The shell is rimate but not deeply, cylindric, rather slender, 

 grayish white, slightly translucent, of 7 whorls, the last 3 or 

 4 flattened, with moderately impressed suture, the last whorl 

 not ascending in front. Sculpture of fine, sharp, closely set, 

 distinctly oblique rib-stria?. The narrow aperture is shaped 

 somewhat like the figure 8. Below the middle the peristome is 

 well expanded. There is a strong but rather short parietal 

 lamella and a small, short lamella near the left upper angle 

 of the mouth, both emerging to the edge of the thin but dis- 

 tinct parietal callus. On the columella there is a small pro- 

 jection above, and a long, obliquely ascending, entering colu- 

 mellar lamella, rather deeply placed. The outer lip arches 



