248 J. S. Gardner — British Eocene Land MoUusca. 



Fam. HELiciNiE. 



Helix (Calocochlea) globosa, Sby. Plate VI. Fig. 6. 



H. globosus, Sby. 1818, Min. Con. vol. ii. p. 157, t. 170. 



The shell is composed of 6 whorls, with an obtuse apex. The 

 whorls rapidly enlarge, each one being more than twice the height 

 of the one above, and the fourth is more than twice the diameter of 

 the third at the suture. The apical angle is very obtuse, but varies 

 considerably within certain limits. The apical whorl seems rounded 

 with the spii-e flat. The succeeding whorls are slightly rounded 

 or flattened, with the sides at angles of 90° and upwards. In some 

 cases the young are subcarniated, in others not, and the aperture is 

 semilunar or subquadrate according to the angularity of the whorl. 

 The penultimate whorl is much more swollen and the sides steeper 

 and higher in proportion, the height being 26 millim., to a diameter 

 of only 46 millim., the one next above measuring but 8 to 33 millim. 

 The height and diameter of the last whorl are little greater than 

 those of the penultimate, producing the globosely-conical outline 

 which has suggested the name. All the specimens are casts, but in 

 a few cases fragments of the shell remain, which are seen to be very 

 finely striated or more roughly marked with lines of growth. There 

 is the appearance of a small umbilicus as a matter of course in the 

 casts from out of which the columella has been dissolved, but one or 

 two specimens with parts of the shell preserved show it to have 

 been imperforate. The suture is well defined. One perfect cast 

 shows the lip to have been considerably reflected in the adult, and 

 there are indications that it was thickened. The aperture is rounded, 

 the peristome discontinuous, the outer lip forming a semicircle, and 

 the columellar lip and the side of the body-whorl cnnvei'ging to an 

 obtuse point at the columella. The base of the shell is very tumid, 

 and when the shell rests upon it, the axis is inclined at an angle of 

 about 25°. The most perfect specimen measures 45 millimetres in 

 height and 46 in diameter, but the extreme diameter of a less perfect 

 one is 62 millimetres. 



Adult shells are very rare and imperfect, and all are from the 

 Bembridge Limestone at Sconce. Young shells are abundant there 

 and also at Bembridge. Though Mr. Edwards has separated some of 

 the casts as H. occlusa, and formulates some pronounced characters 

 by which he says they may be distinguished, I cannot follow the 

 grounds of separation in the actual specimens, and it seems to me 

 that it would be advisable to limit the name H. occlusa to the Headon 

 Limestone specimens, which are quite certainly distinct. 



The shell belongs to the group Calocochlea, now limited to, or at 

 least characterizing the Philippines, and might even belong to the 

 living species which most resembles it, C. Harfordii. There are 

 many other fine species in the same region, and there is a group, 

 Camoena, of shells, in Australia, not disimilar in outline, but um- 

 bilicated. Sandberger compares it to one of the latter, H. Fraseri, 

 of Cape York. 



These, on account of their large size, are the most striking species 



