400 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



Type: Cochlostyla (Helicostyla) mirabilis (Ferussac). 

 I am placing two of the Mindoro Province species here, namely, 

 Cochlostyla (Helicostyla) fulgens (Sowerby) and C. (H.) dimera (Jonas). 



COCHLOSTYLA (HELICOSTYLA) FULGENS (Sowerby) 



Shell varying in shape from broadly ovate to elongate-ovate, im- 

 perforate, the spire with a blunt apex. In the various races before me 

 the ground color of the postnuclear whorls is milk-white; that of the 

 nuclear turns in the fresh state is translucent pale horn color. The 

 spire is covered with a thin, scarcely perceptible film of periostracum, 

 while the base is much more provided with this element. In fact, 

 the base appears as if covered with a heavy coat of varnish. The 

 postnuclear whorls are variously banded with chestnut-brown or 

 almost blackish brown; sometimes a combination of these colors is 

 present on the same shell. In most of our specimens there is but a 

 single band on the spire; in some, however, we have a brown zone near 

 the summit and two or three anterior to this. The base is by far the 

 more variably marked portion of the shell. The columellar area is 

 always dark, and in addition to this there may be one, two, or three 

 bands of varying width present, or these bands may become fused to 

 form a completely dark base or there may be a zone or two of light 

 color. The interior of the aperture is white, frequently showing the 

 dark spiral bands of the outside within. These bands appear to 

 belong to the very substance of the shell. The peristome is white. 

 Nuclear whorls about 1.5, forming an almost flattened apex. The 

 succeeding turns are somewhat inflated and strongly rounded. The 

 periphery is well rounded, and the base is rather short, inflated, and 

 well rounded. The postnuclear whorls are marked by retractively 

 curved, fine microscopic lines of growth and microscopic spiral stria- 

 tions. 



The aperture is oblique, almost subcircular; the outer lip moderately 

 expanded and reflected. The columella is broad, widest in the middle. 

 The parietal wall is covered by a thin, translucent callus. 



This species appears to be confined to the northern and eastern 

 portion of Mindoro. It seems to break up into several races, which 

 may be distinguished by the following key: 



KEY TO THE SUBSPECIES OF COCHLOSTYLA (HELICOSTYLA) FULGENS 



Base covered by a thick olivaceous-yellow periostracum. 



Shell broadly ovate fulgens 



Shell elongate-ovate johnsoni 



Base not covered by a thick olivaceous-yellow periostracum. 



Base covered by a thin yellow periostracum sapolana 



