220 MOLLUSCA FROM THE CRAG. 
Shell transverse, wedge-shaped, and smooth, inequilateral ; posterior side very short 
and truncated ; ventral margin nearly straight and crenulated. 
Length, \ inch. Hetght, $ an inch. 
Locality. Red Crag, Sutton. Recent, Mediterranean. 
This shell is rare in my cabinet, and I have met with it from one locality only. It 
appears to differ from the preceding, and to correspond with the Mediterranean form in 
having a much shorter posterior side, it is also smoother externally, with less distinct 
radiating striae, and the ventral margin not so much curved; the dentition is much the 
same in both species, though somewhat more strongly marked in D. anatinus.* The 
sinus in the mantle mark extends nearly to the middle, rather further beyond the 
hinge than in the British shell, with a few other minor differences ; and as the British 
Conchologists have separated the recent shells into two species, the fossil forms seem 
to warrant a similar proceeding. Philippi mentions this among the Red Sea Shells 
collected by Von Hemprich and Ehrenberg. 
3. Donax pouitus, Poli. Tab. XXII, fig. 9, a, 4. 
TeLLiIna potiTa. Poli. Test. Sicil., vol. i, p. 44, pl. 21, fig. 14, 1791. 
— VINACEA. Gmel. Syst. Nat., p. 3238. 
Donax compLanaTa. Mont. Test. Brit., p. 106, pl. 5, fig. 4, 1803. 
— — Phil. En. Moll. Sic., vol. ii, p. 28, 1844. 
— uonGa. “ Bronn.” Phil. En. Moll. Sic., vol. i, p. 37, pl. 3, fig. 13, 1836. 
— GuaBra. S. Wood. Catalogue, 1840. 
— pouitus. Ford. and Hanl. Hist. Brit. Moll, vol. i, p. 336, pl. 21, fig. 7, 1848. 
Capsa compLanaTa. G. B. Sow. Gen. of Shells, No. 10, fig. 2. 
PsaMMoBIA PoLITA. Costa. Catal. Test. Sicil., p. 20, No. 14. 
Spec. Char. Testdé elongato-cunetformi, complanatd, levigatd, politd, tenui, inequi- 
laterali ; latere antico longiore ; latere postico angulato ; margine integro. 
Shell elongately wedge-shaped, flattened or compressed, smooth and glossy, thin, 
inequilateral; anterior side the longer, produced; posterior angulated; margin 
smooth. 
Length, \ inch. Height, § an inch. 
Locality. Cor. Crag, Sutton and Gedgrave. 
Recent, Britain and Mediterranean. 
Small specimens not exceeding half an inch in length are abundant at Sutton, but 
fragments indicate a magnitude of at least an inch and a quarter. This elegant shell 
is beautifully glossy in those specimens that are well preserved, but the generality are 
* In the ‘ Hist. Brit. Moll.,’ vol. i, p. 340, the hinge of D. trunculusis said to be destitute of lateral teeth , 
while they are described (p. 332) as being present in D. anatinus. I have not been able to make that distine- 
tion. There is a prominent lateral tooth in my fossil on the posterior side, beyond the ligamental support. 
