BULIMULUS-BOSTRYX-PLATYBOSTRYX. 129 



d. Shell narrow, Melania-shaped, regu- 

 larly tapering; subimperforate ; colu- 

 mella subtruncate, Geopyryu*, p. 135. 

 '/'/. Shell narrow and elongated, convexly 

 tapering, perforate, Peroim'tix, p. 138. 

 ddd. Shell with obese body-whorl, unibili- 

 cate or perforate, Ll-^oncme, p. 



Section 1. PLATYBOSTRYX Pilsbry, 1896. 







Wider than high, with broad, crater-shaped umbilicus ; the top 

 flattened with mamillar apex, the last whorl acutely keeled at 

 periphery and base. 



B. EREMOTHAUMA Pilsbry, n. n. PI. 44, figs. 83, 84, 85, 86. 



Shell wider than high, with a broad crater-shaped iunh!/irn., 

 acutely carinated periphery and bate, low spire, and descending last 

 whorl. White, or with flesh-colored suffusion in places ; solid but 

 thin, calcareous. Surface lusterless, rudely wrinkle-striate above, 

 the wrinkles cut and festooned by a group of spiral incised striae ; 

 the lower surface vertically, irregularly plicate, and often with some 

 short transverse wrinkles. Spire low-convex, the apex mainilli\ 

 projecting, smooth. Whorls 4-1, rapidly widening, the latter two 

 concave above ; last whorl with very acute, pinched peripheral and 

 basal keels; its latter third or half deeply descending. 



Aperture white or brownish inside, subtriangular, oblique, angular 

 above, and acutely so at positions of outer and basal keels ; peri- 

 stome continuous, in contact with preceding whorl at its upper angle 

 only ; upper margin simple, outer slightly expanded, columella mar- 

 gin arcuate and expanded. 



Alt- 10, diam. 14 mill. (type). 



Alt. 11, diam. 12 mill. (Hidalgo). 



Cachinal de la Costa (Phil.) ; Paposo (Phil., Paz.), Desert of 

 Atacama, Chili, under stones and among the roots of plants. 



Helix reent*)'! PHIL., Anales de la Univ. de Santiago, 1855, p. 

 213; Malak. Bl.,1856, p.52, 152; Reisedurch die Wiiste Atacama, 

 1860, p. 182, pi. 7, f. 8. PFR., Monogr., iv, p. 182. HIDALGO, 

 Moluscos del Viaje al Pacifico, p. 22, pi. 1, f. 4-5. Not Jiu/!iin< 

 reentd Phil., 1851. 



Hidalgo records a form measuring, alt. 9, greater diam. 15, lesser 

 13 mill. ; spire flat, last whorl less descending, umbilicus wider, 

 peristome more adnate. 

 9 



