4 MOLLUSCA FROM THE CRAG. 



reflected or thickened, more especially at the lower and inner part of the mouth. The 

 perfectly smooth appearance of the specimen is in all probability the result of attrition. 

 A recent specimen from Ayrshire, much depressed in form, has been obligingly 

 sent me by Wm, Thompson, Esq., of Belfast, which very strongly resembles our 

 Crag shell. 



4. Helix eysa. 8. Wood. 1847. Tab. I, fig. 1. 



H. Testa orbiculato-depressd, perforata, supra convexd, radiatd, rugosd, seu corrugatd ; 

 subtus rotundatd, profunde, umbilicata et subtilissme striata ; anfractibus septem obtuse 

 carinatis, carinis prope suturam distinctis ; aperturd subdepressd, late lunari ; peritremate 

 acuto, rcjlexo. 



Shell orbiculato-depressed, perforated, convex, rugosely striated, or rather corru- 

 gated, on the upper half of the volutions, rounded, and faintly striated on the under 

 surface, with a large and deep umbilicus ; volutions seven, obtusely but distinctly 

 keeled ; keel visible at the suture on the upper side; aperture broadly lunate, with a 

 sharp and reflected peritreme. 



Diameter, f of an inch ; elevation, \ ditto. 



Locality. Red Crag, Walton Naze. 



The elegant and, as far as I know, unique specimen, from which the figure above 

 referred to was taken, is from the cabinet of G. S. Gibson, Esq., of Saffron Walden, 

 who has kindly intrusted me with this rarity for publication. It was found, he 

 informs me, in the interior of a specimen of Buccinum undatum. 



By careful examination, as well as by the assistance of my conchological friends, I 

 have been unable to find a species with which this could be identified. In compar- 

 ing it with //. rufescens, the shell to which it appears to have the greatest affinity, 

 some essential differences exist ; it is rather larger, and has seven volutions, where- 

 as in that species I have never been able to obtain a specimen with more than six ; 

 it is more distinctly and roughly corrugated on the upper surface, and the keel, 

 though obtuse, is visible up the spire ; the lines of growth are not more prominent 

 upon the under surface than those upon H. rufescens, where there is a strong resem- 

 blance between the two. In this the aperture is of the same form, though the 

 peritreme is rather more reflected, and a little depressed at the suture. 



Cyclostoma,* Lam. 1799. 



Cyclostoma elegans, Drap. 



Specimens of this well-known species are found in the upper part of the Coral- 

 line Crag, as well as of Helix crystallina. Pupa marginata, and Cyrena trigonula, in 

 association with marine species. The locality from which they were obtained is rather 

 a doubtful one, and from their very recent aspect they must, at least for the present, 



* Etym. KukXos, a circle, aud arofxa, a mouth. 



