156 EOCENE MOLLUSCA. 
2. AstarTe ponacina, J. Sowerby’s MS. Tab. XXIV, fig. 10 a, 6. 
ASTARTE DONACINA, Prestwich. Quart. Journ. Geol. Soc., vol. iii, p. 401, 1847. 
— — Morris. Catal. Brit. Foss., p. 188, 1854. 
Spec. Char. A. testd transversd, inequilaterali, crassd, irregulariter quadrangulata 
aut donaciformi, partim levigatd, compressiusculd ; pedi-regione brevi, alterd longiore, 
subtruncatd ; marginibus crenulatis. 
Shell transverse, inequilateral, thick and strong, of an irregularly quadrangular out- 
line, slightly inclining to wedge-shape; pedal region short and rounded; siphonal side 
truncated ; margins crenulated. 
Length, \ inch nearly. 
Locality. Uondon Clay; Railway Cutting, Old Basing, near Basingstoke (Prest- 
wich). 
This is an elegant shell. About half a dozen specimens have been procured by 
Mr. Prestwich, which he has kindly put into my hands for examination. It is, I think, 
quite distinct ; and as it has passed under the MS. name of donacina, 1 have here 
adopted it. There is a difference in size among the specimens, all of which have a 
crenulated margin; but whether the smaller ones be young and immature—thus pre- 
senting an exception to the rule previously laid down—I cannot positively say ; but 
I think they are all full-grown specimens. Mr. Prestwich said they came from an 
horizon about fifty feet higher than that at Clarendon. 
3. AstarTE ruGATA, J. Sowerby. Tab. XXIV, fig. 13 a—/ 
ASTARTE RUGATA, J. Sow. Min. Conch., t.316. 1821. 
Spec. Char. A. testé crossd, rugatd, rotundato-triangulata ; pedi-regione rotundatd, 
siphoni-regione subtruncatd ; inequilaterali ; in juventate rugatd, vel sulcatd ; umbonibus 
subprominentibus ; lunuld concavd, profundd ; margine crenulato. 
Shell thick, roundedly triangular; pedal region rounded; siphonal side subquadrate 
or truncated; inequilateral; in the young state ridged or sulcated; umbones rather 
prominent ; lunule deep and concave ; margins crenulated. 
Diameter, 1 inch. 
Locality. Wondon Clay: Highgate, Hampstead, Potter’s Bar, Sheppey (Ldwards). 
Mr. Sowerby, in ‘ Min. Conch.,’ has figured several sizes of this shell, which are no 
oubt from specimens of various ages; the larger one only has the inner margin, with 
