J. S. Gardner — British Eocene Land MoUiisca. 251 



angles to the suture and almost parallel to the axis. The ribs are sharp, 

 narrow, and relatively high, and the interspaces are at least three 

 times as wide as the ribs, and five are included in a millimetre. 

 It possesses a projected ovate aperture with slightly reflected lips, 

 which are toothed. There are many living species scattered over 

 the world, but the fossil most closely resembles a group of nearly 

 related species inhabiting the Grecian Archipelago. 



Pupa monodonta, MS., Edwards, froui Headon, appears referable 

 to the genus Megaspira, possessing the columellar folds or teeth 

 characteristic of that genus. ■ 



Megaspira cylindrica, MS. Edwards. — The unique specimen 

 known is from the London Clay of Einchley, and is a small turrited 

 finely striated shell with peculiar transversely plaited columella, 

 appearing identical with M. exigiia from Ports Molle and Curtis. 



Fam. SucciNiN^. 

 SucciNEA IMPERSPICUA, S. Wood, is a true Succinea, very probably 

 belonging to a still existing species, but the living forms are so in- 

 distinguishable from each other, and the genus is so widely distributed, 

 that an exact identification would be difficult, if not impossible. The 

 fossils are from Headon and Hordwell. 



Fam. OLEACINIDiE. 



ZuA. — Two small species, Z. Headonensis and Z. duhia, Edw. MS., 

 smooth cylindrical shells, ai'e referred to the very limited recent 

 genus Zua, but the propriety of this determination appears doubtful. 



All the preceding species require further correlation with those 

 ali'eady described from Tertiary beds of other parts of the world, 

 more particularly with those of the Eocene Paris Basin, as it seems 

 hardly possible, in view of the number of plants common to English 

 and European Eocenes, that so many should be peculiar to so limited 

 an area. There is no doubt but that an exhaustive comparison would 

 enable many more of the fossil species to be identified with living. 

 Very few, I believe, would be found wholly extinct, for the per- 

 sistence of specific types of land snails through long geological ages 

 is one of the noteworthy facts in the history of Moilusca. Many of 

 the genera are known to have existed indeed in the Carboniferous. 

 The facts already brought to light demand a veiy complicated redis- 

 tribution of land and water, and are certainly incompatible with Mr. 

 Wallace's views of the permanence of continents through all geolo- 

 gical time. I prefer for the present however to withhold those 

 more definite conclusions which the material, even so far as already 

 examined, would justify me in putting forward. 



EXPLANATION OF PLATE VI. 

 Land Moilusca from the Upper Eocene, Bembridge Limestone, Sconce, I. of Wight. 

 Fig. 1. Bulimus (Amphidromus) Imvolongus, Boubee, lSi4. 

 ,, 2. Glandina cosleUata, Sowerby, sp. 

 ,, 3. Bulimus {Amphidromus) ellipiicus (young), Sby. sp. 

 ,, 4. „ ( „ ) „ (adult). 



,, 5a. "Egg oi B. ellipiicus {?). db. Section through same. 

 ,, 6. Helix {Calocochled) plobosa, Sby. 

 ,, 7. Clausilia stviatuhi, Edwards. 



All drawn natural size. 



