PSEUDOMELANIA. 
243 
PI. XIX, fig. 1 &, represents a specimen from the clypeus-grit of Xailsworth 
Hill in which there is a still further change in the direction of Ps. Lonsdalei. But 
this form differs from all others related to Fs. coarctata in the relative length of 
the whorls, and also apparently in the greater width of the flexuous lines. Too 
much importance should not be attached to the latter feature in a corroded 
specimen. 
Distribution. — The typical form is nowhere abundant in England, being 
almost exclusively confined to the Htimphriesianus-zone. The best and most 
numerous specimens are from the Cado7nensis -bed at Oborne. 
180. PsEUDOMELANiA Lonsdalei, Morris and Lycett, 1851. Plate XIX, fig. 2. 
1851. Chemnitzia Lonsdalei, Morris and Lycett. Great Ool. Moll., p. 49, 
pi. vii, fig. 13. 
1851 ? — ScAEBDEGENSis, Morris and Lycett. Op. cit., p. 115, pi. xv, 
fig. 8. 
1882. — LiNEATA-PEOCEEA, var. ScAEBDEGENSis, Hudleston. Geol. 
Mag., dec. 2, vol. ix, p. 243, pi. vi, 
fig. 4. 
The essential difference between Ps. Lonsdalei and Ps. coarctata consists in 
the softening of the posterior bevilled edge, and the development of a well- 
defined median sulcus in the whorls, which has the effect of dividing the whorls 
into a posterior and anterior area, the latter being slightly the larger. These 
conditions are perfectly fulfilled' in the specimen (PI. XIX, fig. 2) from the 
Scarborough Limestone of Pickering Cliff in Cloughton Wyke. It is precisely 
like specimens from the Great Oolite of Minchinhampton. (X.B. The median 
sulcus is not shown sufficiently well in the figure.) The following are the 
dimensions : Spiral angle, 16°; height of whorl to width, 1 : I"4 ; length, 85 mm. 
As Chemnitzia Scarhurgensis is founded on a cast from the same horizon and 
locality, the specimen is very likely to have been a cast of this species. A fine 
specimen from the same place was figured and described by me as Ghem^iitzia 
lineata-procera, var. Scarhurgensis. This was certainly “ lumping.” The figure 
is now reproduced (PI. XIX, fig. 3). It differs from Ps. Lonsdalei, found in the 
same place, and might pass for a very narrow variety of Ps. coaixtata. 
