SAINT HELENA. 539 



I think that Mr. Melliss has fallen into some mistake re- 

 garding this Helix, — for he cites it as a subfossil species, found 

 in company with the H. heleiisis or jpolyodon, at the edges of 

 the Sidepath-road above the Briars : whereas if we turn to 

 Pfeiffer's original diagnosis, in the 4th volume of his Mono- 

 graph, we perceive that it was drawn-out from recent examples 

 which were taken by Mr. Cutter on Diana's Peak, — a habitat 

 which would of itself prove, as in the case of the H. dianw, that 

 it could not possibly belong to the extinct fauna. Like most 

 of its immediate allies, it is small in stature (being about 2 lines 

 broad, and li high) ; and it is described as thin in substance, 

 rather closely costate, free from gloss, and of a chestnut brown 

 though tessellated above with a few yellowish markings. But 

 its main feature consists in its aperture being armed with four 

 plaits on the ventral wall, — the two upper ones of which are 

 acute, and the two lower ones more dentiform and placed near 

 to the columella. The following diagnosis of it is taken from 

 Pfeiffer's Monograph : — ' T. perforata, conoideo-depressa, tenuis, 

 subconferte chordato-costata. baud nitens, castanea, superne 

 luteo-tessellata, subtus obsolete undulato-strigata ; spira breviter 

 conoidea, vertice subtili ; anfr. 5\ convexi, ultimus non descen- 

 dens, basi convexiusculus ; apertura vix obliqua, lunaris, laminis 

 2 acutis parietalibus intrantibus, et 2 dentiformibus basalibus 

 prope columellam, coarctata ; perist. simplex, rectum, margini- 

 bus remotis, columellari superne vix dilatato.' 



Patula polyodon. 



Helix polyodon, Soiu., in Danoiyi's Vole. IsL, Append. 157 

 (1844) 

 „ helenensis, Forbes, Proc. Zool. Soc. Lond. (1851) 

 „ Alexandri, Id., Journ. Geol. Soc. Lond. viii. 198. t. 5. 



f. 9 (1852) 

 „ Helenensis, Pfeiff., Mon. Hel. iii. 144 (1853) 

 „ „ Id., ibid. iv. 154 (1859) 



„ „ Id., ibid. vii. 256 (1876) 



„ „ et polyodon, Melliss, St. Hel. 120 (1875) 



Habitat in solo conchylifero versus borealem insulse ; settii- 

 fossilis. 



Although of such diminutive bulk as compared with that 

 species, the present minute Patula (which measures only about 

 1^ line across its broadest part, and which has been found 

 hitherto in merely a subfossil condition) has somewhat the 

 prima facie contour of the common European P. rotundata, 

 Miill., — its flattened, discoidal outline and closely striated 

 whorls, added to the convexity of its base and the largeness of 



