382 THE TERRESTRIAL MOLLUSCA INHABITING 



It belongs to a small group of Polynesian species, which are characterized by 

 a nodulous or dentate columella. 



The only variation consists of a more or less depressed spire. 



M. SUBCICERCULA, Mousson. 



Nanina subcicercula, ("Mouss."), Schmeltz, Cat. Mus. Godeff., v. p. 91. 



Nanina subcircula, Binnej', Proc. Phil. Acad. Nat. Sci., 1815, p. 248, PI. 20, fig. 1 (Dentition). 



Helix subcicercula, Pfeiffer, Mon. Hel., vii. p. 482. 



This common species was found associated with the preceding, and so far as 

 known is peculiar to Rarotonga Island. 



As the late Dr. Pfeiffer merely quotes the name, I suppose there has not been 

 any description published ; I subjoin the following: — 



Shell imperforate, depressed, thin, fragile, smooth, very brilliant, pellucid, 

 luteous-horny, with or without a few irregular whitish dots ; spire short, convexly- 

 conical, obtuse; suture linear; whorls five, convex, faintly striate, regularly and 

 moderately increasing, last one not descending in front, angulate at the periphery ; 

 base convex, indented at the axis; aperture slightly oblique, lunate, with a faint 

 angle corresponding to the one on the periphery; peristome thin, simple with 

 remote margins ; columella thickened with white callus. 



Major diameter 9, height 5 mill. 



Mr. Binney gives a wrong locality. 



M. VENOSA, Pease. 



Selix venosa, Pease, Amer. Journ. Conch., 1866, p. 290, PL 21, fig. 2. Pfeiflfer, Mon. Hel. vii., 



Helicopsis venosa, Pease, Proc. Zool. Soc, 1811, p 4T5. 



Nanina radians, Schmeltz (not of Pfeiffer), Cat. Mus. Godeff., v. p. 91. 



Extremely abundant on the foliage of bushes, and is widely diffused through- 

 out the inland ravines on Rarotonga. 



The animal is pale cinerous, with lead-colored tentacles, and the lobes of the 

 mantle are freckled with light brown. The foot is elongate, narrow, and in length 

 equals the larger diameter of the shells. The mucous gland is papilliform. This 

 and the preceding species are viviparous. 



Mr. Pease's short description is not very satisfactory ; but his figure is sufii- 

 ■ ciently accurate to identify the species. Having examined hundreds of examples 

 I Ijave failed to discover the " blackish'' lines mentioned by the above author. 



The upper portion of the shell is marked with more or less crowded, exceed- 

 ingly fine radiating and concentric or spiral cinereous lines. The basal portion, 

 which is more shining than above, has the lines more distinctly defined. The 



