1910.] 



NATURAL SCIENCES OF PHILADELPHIA. 



101 



there are more ribs on the jaw. The shell is corneous-brown, sub- 

 acutely angular at the periphery, the angle weakening on the last part 

 of the whorl, behind the lip, where the surface is more strongly striate. 

 Spire convex. There are 6^ to 6+ very slowly widening, slightly 

 convex whorls, the last descending somewhat in front. The aperture 

 has a rather long, concave-topped tooth within the outer lip, its face 

 concave. The basal lip has two tubercular teeth, a little compressed 

 laterally, the inner one smaller. These teeth divide the lower border 

 of the aperture into three nearly equal bays. The parietal tooth is 

 straight or slightly bent inward at the axial end; never V-shaped, as it 

 frequently is in .4. fissidens. Parietal callus thin. The umbilicus is 

 rather wide, contained 4| times in the diameter of the shell. The 

 surface is rather dull, finely striate, the striae appearing more or less 



Fig. 17. — Ashmunella proximo,, Quartzite Peak, Station 1. 



irregular or interrupted under a strong lens. The size varies little 

 from 12 mm. diameter. 



In perfectly fresh young shells a delicate pattern of minute low 

 granules on the upper surface may be seen with some difficulty. Si .me 

 very weak traces of spiral stria- may sometimes be made out on the 

 base. The young shells have a callous rib within the lip, at resting 

 stages, but it is apparently not formed as frequently as in A. fissidens. 



The genitalia were figured hi 1905, pi. 21, fig. 24. Having again 

 examined the individual dissected, we note that the penis was incor- 

 rectly drawn. The swollen basal half is everted (as in pi. 21, fig. 23), 

 hence does not show in the figure. The slender upper portion of the 

 penis is shown, its distal end indicated by a slight node, only indis- 

 tinctly drawn in my figure. With these corrections, it will be seen 

 that the organs are like those of emigrans, fissidens and albicavda. 



