176 



Vitrina. Shell small, very thin, depressed, terminated above by a very 

 short spire, the last whorl very large. Aperture large, rounded oval; the 

 left margin arched, slightly involute. 



V. pellucida. 



ORDER III. TRACHELIPODA. 



The shells of this order are spirivalve, ensheathing. It is separated into 

 two sections, viz. Phytiphaga and Zoophaga. 



SECTION I. TRACHELIPODA PHYTIPHAGA. 



Jlperture of the shell entire; base without any ascending dorsal notoli or canal. 



This section contains ten families, viz. Colimacea, Lymnasana, Melanicina, 

 Peristomiana, Neritacea, Ianthinea, Macrostomiana, Plicacea, Scalariana and 

 Turbinacea. 



COLIMACEA.— Eleven Genera. 



Shell spirivalve, with no other projecting parts on the exterior than the strict 

 of growth; the right margin of the aperture is often recurved, or reflected 

 outwards. 



Helix. Shell orbicular, convex, or conoidal, sometimes globular; the 

 spire rather elevated; aperture entire, transverse, very oblique, contiguous 

 to the axis of the shell; the margins disunited by the projection of the penul- 

 timate whorl. 



H. vesicalis, 

 gigantea, 

 polyzonalis, 

 momozonalis, 

 pulla, 

 lineolata, 

 mutata, 

 pomatia, 

 aspersa, 

 vermiculata, 

 Alonensis, 

 vesicolor, 

 naticoides, 

 picta, 

 aalactitos, 

 hcmaatoma, 



H. melanotragus, 

 extensa, 

 lucana, 

 globulus, 

 melanostoma, 

 cselatura, 

 microstoma, 

 maculssa, 

 Richardi, 

 Bonplandii, 

 planulata, 

 labrella, 

 un^uiina, 

 pellis-serpentis, 

 Senegnlensis, 

 unidentata, 



H. cepa, 



heteroclites, 



discolor, 



lactea, 



zonaria, 



guttata, 



Madagascarensis, 



Javanica, 



Peruviana, 



simplex, 



cidaris, 



citrina, 



algira, 



verticellus, 



olivetornm, 



planospira, 



H. Barbadensis, 

 sinuata, 

 hippocastanum, 

 bidentalis, 

 argilacea, 

 vittata, 

 arbustorum, 

 candidissima, 

 memoralis, 

 hortensis, 

 sylvatica, 

 pisana, 

 splendida, 

 serpentina, 

 niciensis, 

 variabilis, 



