A MANUAL OF AMERICAN LAND SHELLS. 53 



HOLOONATHA. 



Family SELENITID^. 



Animal limaciform, with internal shell i)late, or heliciform. No caudal 

 mucus pore. Jaw with or without median projection to cutting edge; 

 no ribs. Lingual membrane with arched rows of teeth. Central tooth 

 small, rudimentary; laterals greatly developed or wanting; marginals 

 aculeate, unicuspid, like those of Glandina. 



Jaw of Liniacidce, with lingual membrane of TestacelUdce. 

 MacrocycUs.* 



Family LIMACID^. 



Naked, with external shell plate, or protected by an external shell 

 partially covered by the mantle, or entirely covered by an external 

 shell, with or without caudal mucus pore. Jaw arched, without ribs, 

 with median projection to cutting edge. Lingual membrane with hori- 

 zontal rows of teeth, or slightly oblique; central tooth tricuspid, central 

 cusp long and slender ; laterals of same height as ceutrals, bicuspid or 

 tricuspid, but in latter case furnished with an obsolete inner cusp; mar- 

 ginal teeth differing from the laterals, aculeate, unicuspid or bicuspid. 



Limax. 



Vitrina. ' 



Zonites. 



Vitrinizonites. 



Family PHILOMYCID^. 



Animal limaciform. Mantle covering whole body; jaw with or with- 

 out anterior ribs, and median i^rojection to cutting edge ; lingual mem- 

 brane of Helicidse; no shell. 

 Tebennophorus. 



Family HELIOID^. 



Animal limaciform or bearing a variously -formed shell, with or 

 without caudal mucus pore. Jaw of various types. Lingual membrane 

 generally with horizontal rows of teeth. Centrals unicuspid or tricuspid, 



* The name Selenites is suggested by Fischer to distinguish the North American 

 species from the true MacrocycUs, which he places among the Eelicidce, Baudonia being 

 preoccupied. 



