COCHLOSTYLA OF MINDOSO PROVINCE 



407 



Subgenus Cochlostyla Ferussac 



In this subgenus the shell varies from ovate to elongate-ovate. 

 The apex is blunt and the aperture broadly oval to subcircular. 

 The peristome is slightly expanded and reflected, while the columella 

 is somewhat excavated. The periphery may be rounded or show the 

 merest suggestion of angulation. The surface is covered with a 

 rather strong periostracum, which shows axial hydrophanous zones 

 that usually extend to the umbilical area. The shells may be unicolor 

 or variously spirally banded. 



Type: Cochlostyla (Cochlostyla) metqformis (Ferussac). 



Only one species from Mindoro Province belonging here is known: 

 Cochlostyla (Cochlostyla) hydrophana (Sowerby). 



COCHLOSTYLA (COCHLOSTYLA) HYDROPHANA (Sowerby) 



Shell ovate or elongate-ovate, covered by a thin hydrophanous 

 periostracum, which is frequently denuded on the early whorls. 

 The nuclear whorls and the early postnuclear turns are white. There 

 is a brown band immediately below the summit and another one at 

 the periphery. These vary in width in different individuals. There 

 is also a median band on the base and a dark columellar area. These 

 bands may be all of the same color, or the peripheral one may be a 

 little lighter than the rest. As a rule they are dark chocolate-brown. 

 The interior of the aperture is bluish white, and so is the peristome. 

 Nuclear whorls 2, well rounded and marked by incremental lines 

 only, except on the last portion of the last whorl, where fine spiral 

 striations are indicated. The postnuclear whorls are strongly rounded, 

 appressed at the summit, and marked by retractively slanting incre- 

 mental lines and exceedingly closely spaced microscopic spiral stria- 

 tions on both spire and base. The periphery of the last whorl is 

 well rounded, and the base is somewhat inflated and strongly rounded. 

 The aperture is subcircular, the outer lip being moderately expanded 



