238 DRYM.EUS, SOUTH AMERICAN. 



simple, outwardly expanded, finally reflexed, so that the left [col- 

 umellar] portion forms a very broad plate over the umbilical chink. 

 The entire shell is uncommonly thin, transparent, glassy and whit- 



ish." (Phil.). 



The locality was unknown to Philippi. Pfeitfer, in Monogr., vi, 

 p. 57, gives Pacific provinces of Mexico, upon w^hose authority does 

 not appear. Yon Martens in 1873 recorded a specimen in Albers' 

 collection from Caracas, Venezuela ; but later he decided that cer- 

 tain specimens from Mirador in eastern Mexico, fulfilled the require- 

 ments of Philippi's diagnosis (see under D. emeus). I am disposed 

 to believe that Philippi's shell is distinct from emeus, and possibly a 

 Peruvian Drymceus allied to cygneus and its allies. 



D. PR^TEXTUS (Reeve). PI. 44, fig. 94. 



Shell umbilicate, conic-oblong, rather solid, rugulose-striate, little 

 shining; flesh-whitish, marbled with violaceous-brown streaks. Spire 

 convex-turrited, the apex rather acute, tawny ; suture lightly im- 

 pressed. Whorls 8, slightly convex, the last a little shorter than 

 the spire, tapering around the somewhat compressed umbilicus. 



Aperture subvertical, oblong, narrow ; peristome simple, the right 

 margin lightly arcuate, narrowly expanded; columellar margin 

 much dilated, reflexed, vaulted. Alt. 39, diam. 14, alt. of aperture 



18 mill. (P/r.). 



Andes of Caxamarca, Peru (W. Lobb). 



Bidimns prcetextus RVE., P. Z. S., 1849, p. 98 ; Conch. Icon., pi. 71, 

 f. 515. PFR., Monogr., iii, p. 344. 



A delicate blue- clouded shell, sprinkled with a few white lines, 

 which are irregularly waved, and sometimes ramified like veins. 



Group of D.fallax. 



-Semiclausaria PFEIFFER, Malak. Blatt., 1855, p.162, type B. 

 subsemiclausus. 



D. SUBSEMICLAUSUS (Petit). PI. 28, fig. 15. 



Shell imperforate, ovate-acute, thin, striatulate ; white, with 

 scattered diaphanous dots and a tawny apex. Spire conic, rather 

 acute; whorls 5, somewhat convex, the last as long as the spire, 

 ventricose, sack-like below. 



Aperture oblong, partly closed, the peristome simple, the right 

 and basal margins angularly bent inward, parietal wall with a 



