1905.] NATURAL SCIENCES OF PHILADELPHIA. 243 



Alt. 5.3, diam. 12 mm. 

 " 5.3, " 12.9 " 

 " 5.8, " 12.9 " 



Chiricahua Mountains, Sawmill Canyon. Tj-pes No. 86,498, A, N. 

 S. P., collected by James H. Ferriss. 



Less carinated than the closely related A. fissidens which is appa- 

 rently a member of the same series. It is difficult to decide on the rank 

 to be given to the members of these chains of modifications of a single 

 type. A. proxima will probably be considered a species eventually. 



There are 14.10.1.10.14 teeth. The side cusps are very short, almost 

 subobsolete on the central teeth. The tenth to twelfth teeth are tran- 

 sitional. Both cusps are split on the marginal teeth. 



The genitalia (PL XXI, fig. 24) of one of the type specimens figured 

 has the atrium protruded. There seems to be an extremely short 

 basal enlargement or penis in another individual opened. The retractor 

 muscle of the penis is very weak. The proportions of the organs are 

 given in the table on p. 224. The very short penis contrasts with A. I. 

 angigyra, which also has more marginal teeth. 



The jaw (PI. XXIII, fig. 17) is thin, with about 5 ribs, of which only 

 two are well developed. 

 Ashmunella fissidens n. 8p. PI. XIV, figs. 67-69. 



Shell depressed, lens-shaped, biconvex, with acutely angular periph- 

 ery; rather thin, brown. Sculptured with fine, irregular growth-lines, 

 the penultimate and next earlier whorls more or less roughened with 

 minute elevated points, as in A. angulata. Spire very low conoid. 

 Wliorls fully 6, closely coiled, moderately convex, the last usually a 

 little impressed above the periphery, wiiich is angular throughout. It 

 is convex below, and deeply guttered behind the reflexed outer and 

 basal margins of the lip. The suture descends a little to the aperture. 

 The aperture is very oblique, much obstructed by four teeth ; an oblique 

 parietal lamella, cm'ved in at its axial end, with, in old specimens, a very 

 low converging ridge outside of it, the two arranged AMike ; a long, 

 square-topped or concave-topped tooth within the outer lip; and two 

 contiguous teeth on the basal lip, slightly united basally the outer one 

 thick and higher, the inner low and more spreading. Parietal callous 

 distinct. 



Alt. 5.3, diam. 12.3 mm. 

 " 5, " 11.5 " 

 " 4.9, " 11.7 " 



Chiricahua Mountains, in Cave Creek Canyon. Types No. 87,022, 

 A. N. S. P., collected by James H. Ferriss, February, 1904. 



