MUSEUM OF COMPARATIVE ZOOLOGY. 177 



The jaw is of the same type as described under P. Lansingi, with over 1 '.) 

 ribs. (Suppl., Plate II. Fig. 0.) 



The peculiar lingual membrane also is the same as in that species, with four 

 laterals on each side of the central tooth. (Suppl., Plate I. Fig. N.) 



Punctum, Morse. 



Animal as in Patula. 



Shell minute, umbiUcated, thin, horn-colored, depressed globose; whorls 4, 

 the last not descending ; spire slightly elevated ; aperture rounded ; peristome 

 thin, acute. 



Europe and North America. 



Jaw slightly arcuate, ends blunt, not acuminated, composed of numerous 

 subequal, overlapping distinct plates. 



Lingual membrane as usual in the Helieidce ; bases of attachment sub- 

 quadrate, reflection small, tricuspid in the centrals, bicuspid in the laterals, 

 marginals irregularly denticulated. 



Distinguished by the peculiar free plates of the jaw. 



There are two species of Punctum, conspectum and pygmmum. 



Helicodiscus fimbriatus, Wetherby, var. salmonaceus, Hemphill. 



Plate III. Fig. 8. 



I give a figure of this variety from an authentic specimen. See 3d Suppl., 

 p. 189. 



Anadenus, Heynemann. 



Animal limaciform, subcylindrical, tapering behind ; tentacles simple ; man- 

 tle anterior, concealing an internal shell-plate ; no longitudinal furrows above 

 the margin of the foot, and no caudal mucus pore ; a distinct locomotive disk ; 

 external respiratory and anal orifices on the right posterior margin of the 

 mantle ; orifice of combined genital system behind and below the light eye- 

 peduncle. (See Plate I. Fig. 1.) 



Internal shell-plate small, oval, flat, with posterior nucleus and concentric 

 striae. (See Plate.) 



Jaw with numerous ribs. See Plate III. Fig. 5. 



Lingual membrane with tricuspid centrals, bicuspid laterals, and quadrated 

 marginals. (See same.) 



Differs from Prophysaon by its posterior respiratory orifice, by the position 

 of the genital orifice, and by its locomotive disk. 



Himalaya Mountains ; recently found in San Diego County, California, by 

 Mr. HemphiU. 



VOL XXII. — NO. 4. 12 



