80 HELIX-PATULA. 



This is a very remarkable little species, at once recognized by its 

 planorbiforrn appearance, and the detached anterior portion of the 

 body whorl. The upper whorls do not rise above the last, and the 

 suture is remarkably deep. The umbilicus is very wide and open, 

 permitting the convolutions of the whorls to be observed to the 

 apex. Both of the specimens examined exhibited traces of red 

 towards the apex, and there is every probability of the living shell 

 having exhibited more or less of that tint. 



P. LJETISSIMA Smith. PL 36, figs. 6, 7, 8. 



Shell minute, narrowly umbilicated, depressed, subconoid; white 

 with radiating reddish spots above and below. Whorls 5, slowly 

 increasing, a little convex above, separated by a rather deep suture, 

 striated with strong growth-lines ; the last whorl rounded at the 

 periphery, hardly descending in front. Aperture half-lunate, tooth- 

 less; peristome thin, simple, the columellar margin dilated; umbil- 

 icus profound, narrow, one-fifth the diameter of the shell. 



Alt. 2&, greater diam. 4, lesser 3 1 mill. ($m.) 



Sugar loaf Ridge, near the top, St. Helena (extinct). 



P. Icetissima SMITH, P. Z. S. 1892, p. 261, t. 21, f. 4-ib. 



This little species is remarkable for its small deep umbilicus, the 

 toothless aperture, rather well marked lines of growth, the rounded 

 periphery to the body whorl, and the red color markings. These 

 consist of radiating blotches on the upper surface of the whorls, 

 which become rather angular and wavy on the middle and lower 

 part of the body-whorl. ($w.) 



P. APERTA v. Moellendorff. PL 37, figs. 35, 36, 37. 



Shell minute, disk-shaped, broadly umbilicated, the umbilicus 

 shallow, showing all the whorls, its width contained 2} times in the 

 diameter of the shell. Spire almost flat, composed of 3f, slowly 

 increasing, convex whorls, the last rounded at the periphery, not 

 descending in front. Sculptured with delicate and rather close 

 thread-like rib-striae in the direction of growth lines. Color whitish. 

 Aperture small, oblique, round-lunar ; peristome simple, thin, the 

 columellar margin dilated. Alt. 0'55, diam. T5 mill. 



Montalbart, near Manila, Luzon. 



The above description and the figures are drawn from specimens 

 kindly furnished by Dr. v. Mollendorff. The species is remarkably 

 depressed, the umbilicus is wider and the aperture smaller than in 



