1905.] 



NATURAL SCIENCES OF PHILADELPHIA. 



229 



"Like rhyssa in size and form, but umbilicus wider, exposing the 

 penultimate whorl ; sculpture finer, consisting of striae rather than 

 riblets. One specimen, diam. max. 15, min. 12f , alt. 9 mm." 



Lower slopes of Sierra Blanca, New Mexico, above head of Ruidoso 

 creek, in aspen belt, about 9,500 feet altitude. (Prof. C. H. T. Town- 

 send, August 14, 1898.) 



The original description is given above. The unique type specimen 

 was lost. Prof. Cockerell subsequently described what seems to be the 

 same race, or one excessively similar, as A. hyporhyssa edentatn, with 

 mutations rufescens and alba, from Cloudcroft, Sacramento Mountains. 

 In the absence of any differential feature in the description or measure- 



ments, I assume that the Cloudcroft shells are identical with 

 hyporhyssa. 



A somewhat large series was collected by Mr. H. L. Viereck in James 

 Canyon, at Cloudcroft, Sacramento Mountains, at an elevation of 9,500 

 feet. Two lots were taken, one of a few large specimens (PI, XII, 

 figs. 7, 8), the other of many smaller ones. Compared with A. rhyssa 

 the shells differ in the constantly more depressed last whorl, though the 

 spire may be equally high; the umbilicus is wider at its opening, ex- 

 posing more of the penultimate whorl; the basal tooth is obsolete or 

 very weak, and the parietal tooth is present only as an extremely 

 small vestige in less than 5 per cent, of the specimens. Finally, the 



