1910.] NATURAL SCIENCES OF PHILADELPHIA. 103 



Genitalia (pi. X, fig. 9) not materially differing from A. p. albicauda. 

 The swollen basal portion of the penis is less than half the total length. 

 The penial retractor is less than one millimeter long. 



Ashmunella fissidens Pils. 



Proe. A. X. S. Phila., 1905, p. 243. 



This species was described from "dead" and discolored specimens, 

 thought to be from Cave Creek Canyon, collected by one of us (Mr. 

 Ferriss) in the course of a flying trip through the mountains in the 

 winter of 1904. In 1906 we collected extensively in Cave Creek; 

 a year later Messrs. Ferriss and Daniels did additional work there, but 

 nothing was seen of A. fissidens. The location of the type colony, 

 therefore, remains uncertain. It is likely that the shells were picked 

 up in White Tail Canyon, also hurriedly traversed in 1904. While 

 the prevalent form in White Tail differs from fissidens in several 

 respects, yet near the head of the canyon some exactly similar shells 

 were found by us in 1906. A lot from near the head of the left branch 

 (going up) (near Jim Artel's old camp) is typical fissidens; and we 

 suggest that this be regarded as the type locality in case true fissidens 

 is not hereafter found in Cave Creek. 



In these shells the lip is not produced forward in an angle near the 

 upper insertion, and the upper angle is not filled with a callus; the lip 

 is narrow with rounded face; there is no upper branch developed on 

 the parietal wall, unless very weakly in some old shells; there are 

 fully 6 whorls; the young develop only a weak lip-rib at resting 

 stages. 



Certain forms from much further south, in Shake Gulch, the foot of 

 Bonito Canyon and Limestone Mountain, seem to be referable to 

 A. fisside?is; but they are less angular, becoming rounded behind the 

 lip, and the umbilicus is decidedly smaller. More material is needed 

 to fix their status. 



Ashmunella fissidens albicauda n. subsp. Fig. 19. 



The upper end of the parietal wall stands more or less free and the 

 lip. near its upper insertion, runs forward in an angle; the posterior 

 angle of the aperture is heavily calloused, and the parietal tooth is 

 usually V-shaped by development of a weak upper branch. The 

 young shells form a very thick and heavy callus within the lip at 

 resting stages (fig. 19D). 



Adult shells are invariabl}' acutely angular in front, the angle 

 weakening and almost disappearing on the latter part of the whorl. 

 Behind the aperture the striation is stronger and sometimes amounts 



