64 EOCENE MOLLUSCA. 



in the ' Mineral Conchotomy,' from which the larger figures are taken ; fig. 2 a is from 

 a specimen in the cabinet of Mr. D'Urban. 



Diameter, 2 iuches ; elevation, 2*3 in. 



Localities. — Shalcome (near Ryde) and Sconce, Isle of Wight. 



No. 17. Helix occlusa. F. E. Edwards. Tab. X, fig. 10 a — e, 



H. testa sub-globosd, fulvo uni-fasciatd ; spird prominuld, quinquies vel sexies circum- 

 volutd; anfractibus convexiusculis, ad suturam depressis, obscure ad basin striatis, sub- 

 planulatis ; aperturd semi-ovatd, marginibus parum reflexis: margine columellari wnbi- 

 licum occludenti. 



A sub-globose shell, with a somewhat elevated spire, composed of five or six 

 rapidly enlarging convex whorls, depressed round the suture, and flattened on the 

 base. The surface presents numerous, very faint, oblique, irregular striae, produced 

 by the lines of growth. The aperture is of a regular semi-ovate form, having the 

 margins slightly reflected ; the inner lip spreads over, and entirely closes the umbilicus. 

 The shell is ornamented by a narrow, brownish-yellow band running round the whorls, 

 just above the line of the suture, the colouring matter of which is retained, more or 

 less, in all the specimens I have seen, in which the shell is preserved. 



This is a well-marked species, easily distinguishable when the shell is preserved. 

 The casts, which are more commonly found, resemble those of the young shell of 

 //. globosa, but can be separated from them without difficulty by the flattened base and 

 oblique columella which present a strong contrast with the tumid base, and nearly 

 vertical columella of that species. The smaller number of the whorls and the narrower 

 umbilicus separate it as distinctly from H. Vectiensis and H. Tf Urbani. 



Diameter, 1*2 in.; elevation, § in., nearly. 



Localities. — Sconce and Headon Hill, where it occurs more rarely than any of the 

 preceding species. 



No. 18. Helix tropifera. F. E. Edwards. Tab. X, fig. 3 a — c. 



H. testa orbiculari, supra plano-convexd, subtus convexo-turgidd, umbilicatd: spird plus, 

 minusve elevatd ; anfractibus quinque aut sex, ad peripheriam subcompressis, et carinatis ; 

 aperturd transversa, subtrigond ; marginibus reflexis umbilico magno. 



I have seen two specimens only, both casts, of this Helix ; from the character of 

 the whorls and the aperture it would belong to Lamarck's genus Carocolla, — the 

 Chilotrema of Dr. Leach. It is an orbicular shell, with a slightly elevated spire, 

 apparently variable in height; the upper sides of the five or six whorls, of which it is 

 formed, are nearly flat, and somewhat compressed near the periphery, which presents a 



