NO. 1520. NEW VITRINELLID MOLLUSKS—BARTSCH. 169 



njirrowl}" and openl}' iimbilicated to the very apex. Columellar wall 

 of the umbilicus not flattened nor anguhited at the outer edge, but 

 evenly rounded with the rest of the base. Aperture forming a broad 

 semioval, of which the columellar side forms the short diameter; outer 



- (I 



b 



Fig. 3.— Vitrinella alaskensis. (i, top view; h, side view; c basai, view. 



lip thin and semitransparent; columella slender and curved; parietal 

 wall covered by a thin callus. 



The type and eight additional specimens, Cat. No. 109470, U.S.N.M., 

 were collected 1)y Dr. William H. Dall at Unalaska, Alaska. The 

 type has 3i whorls and measures: Greater diameter. 1.6 mm.; lesser 

 diameter, 1.2 mm.; altitude, 1.2 mm. 



DOCOMPHALA, new subgenus. 



Shell like typical Yitrinella except in the structure of the umbilicus. 

 In yitrinella ss. the columellar wall of the umbilicus is smooth. In 

 the present group it is divided into two parts, the basal half of which 

 is devoid of sculpture, excepting incremental lines, while the inner half 

 is marked by strong, oblique, rounded ribs. 



Type. — Yitrinella {Docomphala) stearnsi. 



VITRINELLA (DOCOMPHALA) STEARNSI, new species. 



Shell depressed, lenticular, a little more convex above than below. 

 The nepionic portion of the shell consists of the first one and a half 

 turns, which are small, slightly convex, and smooth. The turns which 

 succeed the nepionic part of the shell are strongly, obliquely, trans- 

 versely ribbed on the upper side, but these ribs graduall}'' grow weaker 

 as the shell increases in size and disappear entirely after one and one- 

 half turns, the remaining portion being marked by mere lines of 

 growth on the upper surface. Periphery of the last whorl well 

 rounded. Base very gentU" rounded, crossed by rather strong incre- 

 mental lines. Umbilicus wide and open to the very apex, decidedly 

 angulated at the outer margin. The columellar wall is strongly con- 

 caved from the outer angulation to the junction with the preceding 

 whorl, the inner half of it bears a series of strong ribs behind the 

 aperture. Aperature decidedly oblique; outer lip acute, forming a 

 regular semioval of which the parietal wall and columella form the 

 short diameter; columella short, stout, concave; parietal wall covered 



