100 FAUNA OF THE CORNBRASH. 



this species and all the Bullidse of the Cornbrash are on a large scale, and appear 

 to be perfectly simple in the columellar region, and those whose growth is larger 

 may be simply better grown. Of these there are nine from Scarborough and 

 another from Sudbrook. 



Hydatina magnifica, sp. no v. Plate IX, fig. 7. 



Description. — The shell here described was obtained from Bedford, and may 

 perhaps not be a distinct species. It has been cleaned by a mason in the British 

 Museum. It has a total length of 60 mm. and a breadth of 44 mm. The body 

 rises as before into a ridge, whence it slopes downwards to the spire. The surface 

 has numerous rough longitudinals. The shape of the " fruit " more resembles that 

 of a pear than that of an apple. 



Distribution. — Possibly other examples, e. g. from Rushden (1) and " Northamp- 

 ton" (B. M. 2 in. x 1 in.), are the nearest examples. 



Hydatina limitata, sp. nov. Plate IX, figs. 8 a, 8 b. 



? 1850. Bulla undulata, Morris and Lycett, Great Ool. Mollusca (Pal. Soc), p. 18, pi. viii, fig. 8. 



Type. — Length 16*5 mm., breadth 14 mm. Spire almost on the level with the 

 posterior edge of the last whorl ; diameter of spire small, looking only like a groove 

 on the surface. From this line the surface of the last whorl spreads rapidly out- 

 wards, making the posterior end of the aperture fairly wide, but the plane of the 

 aperture meets the penultimate whorl obliquely, though it has no furrow parallel to 

 the suture : on the contrary, in the spiral direction traces of at least five bands of 

 crinkles, indicative of colour bands, can be traced. From Chippenham. In the 

 Museum of Practical Geology (no. 8676). 



Description. — The type is but a small specimen, and is behind others that are 

 larger, belonging to the same species, but the strict limitation of the posterior 

 border of the highest band to the approximate level of the spire holds for them all. 



Distribution. — Three of these specimens are from grey, speckled, softish rock 

 from Chippenham, probably from some boring or excavation. It is not unlike the 

 Cornbrash exposed at Sutton Benger. A specimen collected by the Geological 

 Survey at Templecombe assures us that the species does occur in the Cornbrash. 



Relations. — The limitation of the aperture posteriorly is the main feature of 

 distinction from H. undulata, probably also its greater relative breadth, and its 

 surface features. I can point out no real difference between this species and that 

 figured by Morris and Lycett as Bulla undulata, which even shows the numerous 



