84 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxn. 



of the base is only slightly depressed below the plane of the last 

 whorl; in fact the most convex part of all of the whorls on the base 

 falls almost in an even plane. The turns are separated above and 

 below by well-impressed sutures. Aperture (juite large, suboval, 

 decidedly oblique, angulated at the middle of the outer lip by the 

 slender keel. Columella practically absent; parietal wall covered with 

 a thin callus. 



The type has four and one-fourth whorls and measures: Greater 

 diameter, 6.7 mm.; lesser diameter, .5.7 mm.; altitude, 1.7 mm. 



The type and 196 specimens, Cat. No. 192982, U.S.N.M., were col- 

 lected in Lake Buluan, Rio Grande Valley, province of Cotabato, 

 Mindanao. 



PLANORBIS (HELICORBIS) LUZONICUS Mollendorff. 



Planorhis (Ilippeutis) luzonicus MOllendokff, Nachr. Mai. Ges., XXVII, 1895, 

 p. 120. 



The shells described were collected by natives near the village 

 Libmanan, in the province Camarines, Luzon. The measurements 

 given for the type, which has live whorls, are: Greater diameter, 10.5 

 mm.; lesser diameter, 9 mm.; altitude, 3 mm. 



PLANORBIS (HELICORBIS) MEARNSI, new species. 



Shell lenticular, vitreous, horn color. Whorls increasing regularl}^ 

 in size, the last enveloping the greater part of the previous turns. 

 All of the whorls show evenly coiled on the dorsal surface in the 



Fig, 2.— PLANORBIS (HELICORBIS) MEARNSI. 



extremely regularly conically depressed apex. The last half turn 

 only, deviates from the regular spiral in having the sunmiit gradu- 

 ally deflected until it falls about halfway between the summit and 

 periphery on the preceding turn, at the aperture. The angle at the 

 junction of the outer wall and the parietal wall is filled u]) for a short 

 distance, and this shows through the shell as a moderately broad solid 

 band, and makes the whorls appear as if the}' had a double suture. 

 The whorls are evenly rounded on the dorsal surface and marked by 

 moderatelv strong incremental lines onl3\ Sutures lightly impressed. 

 Periphery of the last whorl bluntly but strongly angulated. Base 

 almost flat, with a moderately broad umbilicus, in which the whorls 

 can be seen regularly and evenl}^ coiled, but here also the last half of 

 the last one becomes more and more openly coiled until it reaches 



