75 * 
PENTAMERUS Aylesfordii. 
TAB. XXIX. 
Spec. Char. Nearly circular^ with longitudinal 
furrows; tripartite valve convex., with a pro- 
minent incurved beak ; bipartite valve gibbous,, 
incurved, conical* with a much incurved beak. 
Nearly resembles the last, differing only in the form of 
the smaller valve, which is more hemispherical, and has 
a more curved beak ; the edges of the two valves meet in 
this, which I suspect is not the case with P. Knightii. 
I think it possible that this may be another species, 
and may accord with some of Mr. Aikin’s specimens from 
Yeo Edge. The largest is in the possession of Lady 
Aylesford, and is the finest I have seen. It is almost ne- 
cessary to break these specimens in order to see their 
strongest characters, nor would Lady Aylesford’s have been 
recognized but for the fracture at the apex, which displays 
the division at the beak. The left hand outline of Tab. 
28 . is the sketch of a section exhibited by a specimen from 
Amestry, in a coarse grey Limestone, among others in the 
possession of G. B. Greenough, Esq., it is of a pink hue, 
prettily relieved by the dark stone; it is filled with a 
crystallized mass of a light colour. Mr. Farey has speck 
mens from Croft- Ambrey Park. 
I cannot learn where Lady Aylesford’s specimen was 
found ; the one of which I have given two views below, 
and which is rather a wider shell, though scarcely different 
enough to be considered a distinct species, was picked up 
by Mr. Ryan at Colebrook Dale. It is from analogy that 
