236 TEST ACE A ATLANTIC A. 



it) being exceedingly prominent, but suddenly truncated, or 

 almost emarginate, internally ; whilst even the inner one is 

 likewise unusually prominent and developed, it being thicker 

 and less immersed (in proportion to the size of the shell) than 

 in any Pw^ct which I have hitherto examined. 



The P. gibba seems, in a recent condition, to be of the 

 utmost rarity ; indeed the only two examples, so far as I am 

 aware, which have as yet been detected were found by myself, 

 amongst loose vegetable detritus, at the base of the lofty per- 

 pendicular rocks towards the head of the Ribeira de Sta. Luzia, 

 in the south of Madeira proper. But although thus scarce in a 

 living'state, it is not so particularly rare in the subfossiliferous 

 beds at Canipal ; though its minute size is apt to render it 

 somewhat liable to escape observation. 



(§ Mastula, Lowe.) 



Pupa lamellosa. 



Pupa lamellosa, Lowe, Ann. Nat. Hist. ix. (1852) 

 „ „ Pfeif., Mon. Hel. in. 556 (1853) 



„ „ Loive, Proc. Zool. Soc. Lond. 214 (1854) 



„ „ Alb., Mai. Mad. 66 (1854) 



„ „ Paiva, Mon. 3Ioll. 3Iad. 138 (1867) 



Habitat Maderam ; recens semifossilisqae rarissima. 



The P. Imnellosa, although short, small, and strongly cos- 

 tate, belongs to a totally different type from any of the preceding 

 species, — its abbreviated, turbinate form (the apex being unusually 

 truncated or immersed), and less hardened texture, added to 

 the tendency of its very oblique and widely separated ribs to be 

 occasionally somewhat foleaceo-dilated in the centre (as though 

 slightly and obsoletely spinulose) and the shortness of its aper- 

 ture (which is rather wider than long, with the lip acute, and 

 exteriorly rounded or unsinuate), giving it a character which it 

 is impossible to mistake. Its three basal volutions are extremely 

 tumid ; and its outer ventral plait (wliich is totally unconnected 

 by a callous sphincter with the angle of the lip) is exceedingly 

 lamelliform and obliquely curved, whilst the inner ventral one 

 (like the palatial ones and the dipper one on the columella) is 

 obsolete,- — the lower columellary one, however, being tolerably 

 developed. The ' sinus ' is hardly at all expressed. 



The P. lamellosa is one of the rarest of the Pu^ce, and has 

 been observed hitherto only in the south of Madeira proper — at 

 intermediate elevations. It has been taken sparingly by Mr. 

 Leacock in the Vasco Gil ravine, — wliere I have myself also met 

 with it, as likewise in the Ribeira de Sta. Luzia. 



