.130 



PROCEEDINGS OF THE ACADEMY OF 



[Sept., 



ture is lunate, the columellar margin thickened near and at its insertion 

 in the center. There are no internal lamellae. 



Alt. 7.3, diam. 13 mm. 

 " 6.9, " 12 

 " 6.9, " 12.3 " 



Somerset, Manchester. Types No. 101,140, A. N. S. P., collected 

 by Dr. A. P. Brown, May, 1910. 



This form is apparently what Professor C. B. Adams described as 

 Helix osculum var. delaminata; but if so this name is barred by the 

 prior //. epistylium var. delaminata C. B. Ad., which is probably a 

 valid species. While the shell under consideration resembles Sagda 

 osculans closely in form, it differs constantly, in a very large series 

 collected in the Mandeville region, by the total absence of internal 

 laminae. The laminate S. osculans was not taken in this region. We 

 have no evidence whatever that the two forms intergrade, and are 

 decidedly of the opinion that both are distinct and valid species. 



Spirostemma mandevillensis »• sp. Fig. 11. 



The shell is pillar-shaped, the diameter contained 6 to 6£ times in 

 the length, widest near the middle, tapering very slowly 

 and slightly towards both ends; brown, rather dark when 

 living; widely truncate above, the breach closed by a 

 strongly convex plug. Whorls remaining are nearly flat, 

 the last one shortly free in front, very strongly keeled, at 

 the base, concave just above and below the keel. The 

 sculpture is of fine, regular, extremely oblique retractive 

 striae, which are about as wide as their intervals. The 

 aperture is small, its greatest length contained 6^ to 1\ 

 times in the length of the shell, very oblique, obovate, 

 being angular below, broadly rounded above. Peristome 

 pale, continuous, narrowly expanded throughout. The 

 internal axis is very slender, nearly straight in the upper 

 whorls. It begins to be sinuous in the seventh, becoming 

 progressively more broadly spiral from there to the last. 

 \5k/ In an obliquely basal view in the mouth a large false 

 Fig. 11. umbilicus is seen, about one-third as wide as the last 



whorl. 

 Length 14.3, diam. 2.2, length of aperture with peristome 1.9 mm.; 

 whorls 12f . 



Length 13.3, diam. 2.25, length of aperture with peristome 2 mm.; 

 whorls \2\. 



