368 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



before the last whorl and a half are reached. The incremental lines 

 are not strong, but the incised spiral lines are well developed and 

 very regular both on the spire and base. The aperture is oval; the 

 peristome, thickened and reflected, covers about half of the umbilicus 

 at the parietal wall. 



Type.— The type, U.S.N.M. No. 382705, and a lot of additional 

 specimens, U.S.N.M. No. 256436, were collected by the writer on a 

 hill on the west shore of Mansalay Bay, Mindoro. The type has 

 5.2 whorls, and measures: Height, 14.3 mm; greater diameter, 27.4 

 mm; lesser diameter, 21.6 mm. 



Remarks. — Twenty-five specimens yield the data given in the table 

 on page 367. 



This subspecies, while it resembles Obba planulata medioensis, is 

 easily distinguished from this by its smoother surface and the very 

 conspicuous interrupted basal band. 



OBBA PLANULATA MEDIOENSIS, new subspecies 



Plate 93, Figure 3 



The shell is depressed-helicoid with the periphery of the last whorl 

 obsoletely angulated. The nuclear whorls are dark buff; the whorl 

 that succeeds them is brown, while the rest of the upper surface is of 

 flesh-colored ground color, blotched, spotted, and vermiculated with 

 dull chestnut-brown. On all the postnuclear whorls a somewhat 

 darker interrupted zone marks the obsolete peripheral angle. The 

 base is soiled flesh-color with a moderately broad, interrupted, 

 ill-defined, dark band about one-third of the distance between the 

 periphery and umbilicus anterior to the periphery. The space 

 between this band and the periphery is indistinctly marked with 

 a few streaks of brown. The peristome is flesh-colored with a 

 brownish flush, while the inside of the outer lip is pale brown with a 

 purplish wash. The postnuclear whorls are weakly malleated on the 

 anterior half, except the last turn where this character fades out. 

 The postnuclear whorls are also marked by rather coarse and irregular 

 incremental lines and strongly incised wavy spiral lines, which are 

 present on both spire and base. Aperture moderately large, oval; 

 peristome reflected over about one-third of the umbilicus. Tooth 

 on the inner lip strongly developed. 



Type.— The type, U.S.N.M. No. 382704, and a lot of additional 

 specimens, U.S.N.M. No. 256438, were collected by myself on Medio 

 Island in Galera Bay, off northeast Mindoro. The type has 5.2 

 whorls, and measures: Height, 13.8 mm; greater diameter, 28.4 mm; 

 lesser diameter, 22.6 mm. 



