362 BULLETIN OF THE 



mantle : orifice of combined genital system behind and below right eye- 

 peduncle. 



Shell-plate internal, suboval, slightly convex, small, with posterior nucleus 

 and concentric lines of growth. 



Jaw smooth, with median projection. 



Luigual membrane with peculiarly shaped teeth, centrals tricuspid, laterals 

 bicuspid, marginals acideate, bicuspid. 



Prince's Island. 



For figure of animal contracted ki spirits, jaw, and lingual dentition, see 

 HejTiemann, IMalak, Blatt., XV., PI. I. 



The horn-shaped process only seems to distinguish it from Urocyclus, the 

 position of the respiratory orifice from Parmarion. Dentition peculiar. 



Vitrinoidea, Semper. Animal limaciform, swollen at its middle, slender 

 and tapering behind : tentacles simple ? mantle large, anterior, covering the 

 shell : no longitudinal furrows above the margin of the foot, and no caudal 

 mucus pore : no distinct locomotive disk : external respiratory and anal ori- 

 fices on right anterior margin of mantle : orifice of combined genital system 

 behind and under right eye-peduncle. 



Shell internal, paucispiral, transparent, globose, rudimentary. 



Jaw smooth. 



Lingual membrane with tricuspid central and lateral teeth, and tricuspid 

 aculeate marginals. 



Luzon. 



For figure of animal and lingual dentition, see Semper, Phil. Arch. 



HOLOGNATHA HELICEA. 



Tebennophorus, Bixx. {Incilaria, Bens., Megbnathium, Van Has.) Ani- 

 mal limaciform, cylindrical, blunt before, slightly attenuated behind : tentacles 

 simple : mantle covering the whole back : no longitudinal furrows above the 

 margin of the foot, and no caudal pore : no distinct locomotive disk : external 

 respiratory and anal orifices near the head, somewhat to the rear of the right 

 eye-peduncle : orifice of combined genital system behind and below the right 

 eye-peduncle. 



Shell or shell-plate none. 



Jaw smooth, with median projection. 



Lingual membrane long and narrow, centrals and first laterals unicuspid, 

 outer laterals bicuspid, marginal teeth quadrate. 



Asia, North and Central America. 



For figure of animal, jaw, and lingual dentition, see Terr. Moll. U. S., V. 



Oopelta, Heynem. Body limaciform, subcylindrical, tapering behind: 

 tentacles simple: mantle small, oval, more pointed behind: no longitudinal 

 furrows above the margins of the foot, and no caudal mucus pore: no distinct 

 locomotive disk: external respiratory and anal orifices on the right slightly 

 anterior margin of the mantle : orifice of comljined generative system behind 

 and under the right eye-peduncle. 



