646 bartsch: classification of helicinidae 



In the use of this key care must be taken not to confuse the fine cross- 

 hatch or crinkly short hnes, which are found in varying strength in all 

 the members of the genus, with true incised spiral lines. The junction 

 of the columella and the basal lip in one big series always forms a con- 

 spicuous angle. Members of this group practically always have the 

 columella decidedly excavated. In the other series, the columella 

 passes directly into the basal lip with scarcely an indication of the 

 junction. 



Section I 



In this section, fine incised spiral lines are present. The columella 

 is strongly excavated and forms a conspicuous angle at its junction 

 with the basal lip. The following key will help in the identification of 

 the known forms: 



Greater diameter more than 14 mm. 



Periphery with an obsolete keel hoholensis Bartsch 



Periphery with a strongly compressed keel 



Base decidedly inflated pachychilus Mollendorff 



Base not inflated 



Greater diameter more than 16 mm roniblonensis Bartsch 



Greater diameter less than 15 mm mindoroensis Wagner 



Greater diameter less than 12 mm. 



Spire rather elevated negrosensis Bartsch 



Spire rather depressed 



Shell yellow nitidulus Mollendorff 



Shell japan rose versicolor Mollendorff 



The specimens of this section fall readily into two groups, one em- 

 bracing large shells, in which the diameter is always more than 14 mm., 

 and one in which the diameter is always less than 12 mm. There are 

 four species of the larger forms. Of these, the specimens from Bohol, 

 Geophorus hoholensis n. sp., have the peripheral keel obsolete and the 

 base decidedly inflated. No depression is present at the junction of 

 the base and the peripheral keel. This is the largest of the four species. 

 The type, Cat. No. 104419, U. S. National Museum, has 5.1 whorls 

 and measures: altitude, 10 mm.; greater diameter, 16.5 mm. 



The other three species have the peripheral keel very strongly de- 

 veloped. One of these, Geophorus pachychilus Mollendorff has the base 

 strongly inflated and but slightly concaved at its junction with the 

 peripheral keel. This species comes from the island of Guimaras. A 

 typical specimen of this species, Cat. No. 258761, has 5.3 whorls and 

 measures: altitude, 16.3 mm.; greater diameter, 14.7 mm. 



