218 HKLICOSTYLA. 



other incongruous elements, leaving only H. alnuda and its varieties 

 and H. mirabilis (galactites), and adding smaragdus and roissyana. 

 Albers in 1850 restricted Helicostyla to Philippine Island snails of 

 the mirabilis type, erecting for the W.est Indian H. alauda the new 

 group Coryda. H. & A. Adams make Helicostyla a genus to include 

 Calocochlea, Corasia, Axina, Chlorcea, etc., and place the elongated 

 forms in genus Cochlostyla under Bulimina?. 



Cochlostyla was instituted by Ferussac on the page of the 

 Tableaux after Helicostyla, and contained species belonging to the 

 groups Helicostyla, Helicobulinus, Orthostylus, Cylindrus, Caryo- 

 des, Orphnus, Dryptus, Orthalicus, etc. The name dropped out of 

 nomenclature entirely until 1847, when Gray names it under 

 Orthostylus, giving metaformis as its type. Later, the Adams 

 brothers revived it as a genus for elongated Philippine Island forms ; 

 and in 1860 von Martens uses it in much the same sense. In 

 enlarging the genus to include both depressed and elongated species, 

 Semper unfortunately retains the name Cochlostyla for the entire 

 series, a course which has been followed by subsequent writers. 



In conclusion it is evident that for this genus we must use the 

 name Helicostyla, which not only has prior position in Ferussac r s 

 work, but was restricted in 1837 by Beck and properly limited by 

 Albers ; while Cochlostyla was later in the original publication, and 

 remained a heterogeneous mass of Bulimi and Helicostylie until 

 Gray in 1847 selected metaformis as its type. 



Subdivisions. 



With the exception of Canistrum, the sections of this genus are 

 practically identical in anatomy ; and rest upon such shell charac- 

 ters as contour, thickness and sculpture. The presence of interme- 

 diate species renders their arrangement somewhat artificial. 

 Depressed or globose, thin, without hydrophanous cuticle. 



Globose, white, lip simple and sharp, Pfeijferia. 



Lip expanded or reflexed, Corasia, Crystallopsis. 

 Globose, few whorled, with hydrophanous bands, Leytlo. 

 Globose or depressed, solid, lip expanded or reflexed. 



No hydrophanous cuticle, lip narrow; highly colored. Chromaio* 

 sphcera. 



Hydrophanous cuticle present, lip wider, Calocochlta. 



Dark, depressed and much roughened forms, Trachyxtyfa. 



Dark and smoothish forms. Ani.cn. 



