bartsch: subspecies of leptopoma nitidum 533 



ery vaiying from well rounded to feebly, obsoletely angled in the 

 various subspecies. Base umbilicated, well rounded, usually sculp- 

 tured like the upper portion of the last whorl. Aperture subcircular; 

 outer lip reflected and expanded; inner lip strongh^ curved and decidedly 

 excavated; parietal wall narrow, covered with a thin callus. Oper- 

 culum membranaceous. 



The size of the shell varies from the huge Leptopoma nitidum guima- 

 rasensis from Guimaras Island, to the small Leptopoma nitidum 

 ancilis from Cebu. 



The character of the incised spiral sculpture, particularly that of the 

 last whorl, enables one to separate this complex into three distinct 

 groups. In the first of these, the incised lines are deep and rather 

 distantl}^ spaced. This group embraces, L. n. siquijorensis from 

 Siquijor Island, L. n. guimarasensis from Guimaras Island, and L. n. 

 darajuayensis from Darajuay Island. 



The second group has the incised spiral sculpture of the same strength 

 as in the first group, but the striations are more closely placed and 

 these, in connection with the lines of growth, are so arranged as to 

 give the surface of the last whorl the appearance of a cloth-like texture. 

 There are seven subspecies belonging to this group, L. n. atropos from 

 Polillo Island, L. n. cebuensis, from Cebu Island, L. w. hutauananensis 

 from Butauanan Island, L. n. bnsiaoensis from Basiao Island, L. n. 

 macidahoensis from ]\Iaculabo Island, L. n. leytensis, from Leyte, and 

 L. n. nitidum from northern Luzon. Of these, the first three have an 

 obsolete spiral thread at the periphery while the last four have this 

 portion of the shell evenly rounded. It is interesting to note that in 

 some of these forms the spiral lirations characteristic of the nepiojiic 

 whorls of all the members of the nitidum group, extend beyond the 

 nepionic portion of the shell. 



In the third and last group, the spiral sculpture is feeble and consists 

 of feebly incised, wavy lines. This group embraces five subspecies, 

 L. n. romblonensis from Romblon Island, L. n. panayensis from Panay 

 Island, L. n. anaitis from Cebu, L. n. unionensis from Luzon, and 

 L. n. artemisia from the small island of Panay, of the Catanduanes 

 Group, off Eastern Luzon. 



Key to the subspecies of Leptopoma nitidum Sowerby 



Spiral sculpture consisting of strong, deeply incised lines. 

 Spiral striations distantly spaced on the last whorl. 



Nepionic whorls brown 1. siqxiijorensis 



Nepionic whorls white. 



