62 DRYM^EUS, MEXICO AND CENTRAL AMERICA. 



D. TRIMARIANUS (von Martens). PI. 2, figs. 17, 18. 



Shell riinate perforate, ovate-fusiform, rather thin, lightly striatu- 

 late, somewhat shining ; white, usually painted with fragments of 

 interrupted bands. Spire attenuated, rather acute, the apex pale. 

 Whorls 7, a little convex ; suture impressed, delicately and irregu- 

 larly crenulated, the last whorl moderately attenuated at base. Aper- 

 ture nearly vertical, less than half the total length of the shell, oval- 

 oblong; peristome a little thickened, narrowly expanded, white ; 

 columellar margin nearly straight, a little thickened, reflexed, half 

 covering the perforation (Martens). 



Alt. 32, diam. 14, length of aperture 14J, breadth 7 mill. 



Alt. 27, diam. 12, length of aperture 12J, breadth 7 mill. 



N.-W. Mexico: Tres Marias Islands (Forrer and Richardson). 



Otostomus trimarianus v. MART., Biol. Centr. Amer., Moll., p. 

 216, pi. 13, f. 17 (August, 1893). 



" This species almost forms a connecting link between Otostomus 

 attenuatus, 0. serperastrum and 0. pallidior Sow. the latter from the 

 Peninsula of Lower California ; it resembles 0. attenuatus but has 

 not its thread-like, twisted, columellar margin. From 0. pallidior 

 it is distinguished by the less conical, in the last whorl much more 

 oblong, form, the thinner shell, and the narrower aperture ; from 0. 

 serperastrum also by the general shape of the shell. Some specimens 

 are entirely white; others' have more or less distinct traces of pale 

 brown spots on the penultimate whorl arranged in four spiral rows, 

 corresponding in position to those of 0. serperastrum (the fifth and 

 sixth being covered by the following whorl) but they do not extend 

 over more than half the whorl in the spiral direction " (Martens.) 



D. HEPATOSTOMUS (Pfeiffer). PI. 2, figs. 23-27. 



Shell perforate, subfusiform-oblong, rather solid, smoothish ; white, 

 marked sparsely with brown streaks. Spire conic, rather acute ; 

 suture subnaargined. Whorls 6, moderately convex, the last a little 

 longer than the spire, somewhat tapering at base. Columella verti- 

 cal, straightened. Aperture scarcely oblique, oblong, liver-colored 

 inside, glossy ; peristome white, the right margin narrowly expanded, 

 columellar margin flat, broadly reflexed. 



Alt. 32, diam. 13, length of aperture 17 mill. (Pfr.) 

 S. Mexico: Tepanistlahuaca (Boucard); Juquila, State of Oaxaca 

 (Hoge). 



