74 Bulletin 39 246 



quite wide, spiral bands; on the last whorl there are about 22 

 spiral bands; much finer near the suture, larger and wider on 

 the middle of the whorl and on the canal; canal short and slight- 

 ly bent to the left; inner lip calloused. 



Length 15, diameter 5.5, last whorl 8.5 mm. 



Characterized by its six axial ribs and finer sculpture of flat, 

 spiral bands. It belongs to the genus Cyniatosyrhix of Dall. 



Gatun Stage: Water Cay, Panama. 



Orillla musa, n. sp. Plate 5, figure 26 



Shell about the same size as the preceding but with a 

 more slender spire; nucleus of 2 smooth whorls (broken); post- 

 nuclear whorls about 8; no fasciole; axial ribs about 9, pass 

 from suture to suture and across the base to the anterior canal 

 the ribs are in line across the whole series of spire-whorls; spiral 

 sculpture quite heavy, consisting of raised threads with wider in- 

 terspaces; the spirals number on the spire-whorls 8 or 9, and on 

 the last whorl about 22; aperture large and suboval; anterior 

 canal short, narrow and heavily calloused to form the inner lip. 

 Length 17; diameter 6, last whorl 9 mm. 



Related to the preceding, but differs by its more slender 

 form; with 9 instead of 6 ribs and a much coarser spiral sculp- 

 ture. 



Gatu7i Stage: Ba?ia7ia River, C. R. 



Drillia iithocolletoides, n. sp. Plate 5, figure 18 



Shell small, glassy or translucent; nucleus of about 3 smooth, 

 convex and glassy whorls, followed by 6 post-nuclear whorls; the 

 whorls are strongly angled in the middle by tubercular-like ribs 

 but leaving a concave zone about the upper sutures which forms 

 the anal fasciole; on the last whorl, the ribs or tubercles number 

 II ; are set obliquely and on the back of the whorl, they are con- 

 tinued slightly over the base; the surface is smooth and polished; 

 last whorl slightly constricted above the short, straight canal; 

 aperture subovate. 



