58 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



thin lip, it recalls G. corticaria, which is perhaps the species 

 most nearly related. The angulo-parietal lamella is simple, as 

 in pentodon or pilsbryana, or sometimes the extremely minute 

 trace of the forward end of the parietal lamella appearing as 

 a branch on the colurnellar side, may be seen near the outer 

 end. The lower or free edge of the parietal lamella is bent 

 towards the columella as in G. cristata. The lower palatal 

 fold is usually rather long. The columellar lamella is trans- 

 verse, as in the procera group, and there is no callous below it. 

 In a great number I have seen, none has a basal plica. 



It is a common shell in the heavily-forested and humid 

 upper zone of the Santa Catalina Mountains, north of Tuc- 

 son, and in the Black Range, New Mexico, but very rare in 

 the Chiricahua Range, at the southern limit of the species, 

 where it occurred in Barfoot Park, 10,000 ft. elevation. Its 

 stations are chiefly between 7,000 and 11,000 ft., and never at 

 low levels. 



As the name quadridentata is in use for a species of Gas- 

 trocopta from the German Upper Miocene, I am substituting 

 quadridens, which although used for the species in 1900 quite 

 inadvertently, and with no intention to form a new name, 

 may serve now that the original name is not admissible. 



I have a strong suspicion that this species, like G. corticaria, 

 belongs to the same stock as Sinalbinula and Vertigopsis, and 

 should form another subgenus; yet for the present it is left 

 with the rupicola, group, which it resembles in general fea- 

 tures, 



17. GASTROCOPTA RUPICOLA (Say). PI. 11, figs. 1, 2, 3, 5, 6. 



' ' Shell dextral, attenuated to an obtuse apex, white ; whorls 

 six, glabrous; suture deeply impressed; labium bidentate; 

 superior tooth lamiform, emarginate in the middle, and at the 

 anterior lip obsoletely uniting with the superior termination 

 of the labium ; inferior tooth placed upon the columella, and 

 extending nearly at a right angle with the preceding ; labrum 

 tridentate, teeth placed somewhat alternately with those of 

 the labium, inferior tooth situated at the base and imme- 

 diately beneath the inferior tooth of the labium. Length, 

 one-tenth inch" (Say}. 



