1905.] 



NATURAL SCIENCES OF PHILADELPHIA. 



227 



account of his collecting in Utah, and by Ferriss, who in speaking of the 

 Huachiicas says, "Every colony in the canyon was liable to have some 



distinctive mark in size, color or form No two colonies seemed 



exactly alike, and they did not visit back and forth, nor travel far from 

 the best part of their own rock pile" {Nautilus, XVIII, p. 51). 



When through some means two slightly differentiated colonies inter- 

 mingle, as they occasionally must, hybridism follows, and a complex 

 progeny issues, such as I have found in the Floridian Liguus. WTio 

 can unravel the tangled threads of affinity when the modified forms of 

 two or more canyons reach each other across a divide ! It is as complex 

 as a modern human commimity, where subraces are mingling blood 

 after centuries of pure breeding. 



Growp of A. rhyssa. 



In species of this group, small basal and parietal teeth are often 

 present, but there is no outer lip tooth. The spermatheca and its duct 

 are about half the length of the penis, epiphallus and flagellum, or even 

 less. The combined length of the penis, epiphallus and flagellum is 

 decidedly less than three times the diameter of the shell. The penis 

 is comparatively well developed. 



This group is especially characteristic of the Capitan, White and 

 Sacramento ranges of southern-central New Mexico, east of the Rio 

 Grande. The forms now known arrange themselves in three series, 

 thus : 



robusta 



ashmuni 



capitanensis hyporhyssa altissima 



pseudodonta 



miorhyssa- 



-rhyssa- 



-townsendi 



The central and right-hand groups are known to be related by the 

 genitalia. The group on the left is separated from these geographically, 

 and its relationships must remain wholly uncertain until the soft parts 

 can be examined. 

 Ashmunella rhyssa (Dall). PI. XII, figs. 1-4. 



Polygyra rhyssa Dall, Nautilus, XI, May, 1897, p. 2. 



Ashmunella rhyssa Dall, Pils. and Ckll., Proc. Acad. Nat. Sci. Phila., 1899, 

 p. 192; DaU, Proc. U. S. N. Mus., XXIV, p. 500, PL 27, figs. 11, 14. 



