164 SUPPLEMENT TO THE CRAG MOLLUSCA. 
Puonas parva, Pennant. Supplement, Tab. X, fig. 26. 
PHOLAS PARVA, Penn. Brit. Zool., vol. iv, p. 77, pl. xl, fig. 13? 
—  DAcTYLOIDES, Desh. 2nd ed., Lam., vol. vi, p. 45. 
— LIGAMENTINA, Id. Elem. Conch., pl. iii, figs. 11, 12. 
— TUBERCULATA, Turton. Brit. Biv., p. 5, pl. i, figs. 7, 8. 
Length, = inch. 
Locality. Red Crag, Waldrinefield. 
Mr. Alfred Bell and Mr. Charlesworth lately obtained some blocks of clayey material 
from the nodule pits at Waldringfield, in which were lodged several specimens of this 
species, with the valves united in their natural position, and I am indebted to both those 
gentlemen for specimens. 
The Crag fossil corresponds with the short variety of the existing species, which is 
nearly equilateral, but the imbricated radiations are closer and more numerous than upon 
any recent specimen that I have seen. 
Puonas Brevis, S. Wood. Supplement, Tab. X, fig. 24 a, 6. 
Locality. Cor. Crag, Sutton. 
In the ‘ Crag Moll.,’ vol. ii, p. 296, I spoke of a fragment of Pholas crispata having 
been found by myself in the Cor. Crag. ‘This fragment I now believe does not belong 
to that species, and I have had it represented as above (Tab. X, fig. 24 a). I have also 
met with several other large fragments and some small perfect specimens (one of which I 
have figured 24 6) which appear to me to be the young of the same species, although in 
these young specimens the imbricated radiations approach much nearer to the dorsal 
margin on the siphonal side than they do on the large fragment. In the latter, however, 
they are faintly visible over this part, and may have become obsolete during the growth 
of the shell. The small specimens show a highly reflected dorsal edge behind the 
umbonal region, but this part is broken off in the larger specimens. In our present 
species the imbricated rays cover, even in the adult shell, as shown by the large fragment, 
more or less of the posterior half of the shell, which is not the case with cr¢spata. In 
other respects the large fragment resembles crespata. ‘The proportions also of both the 
figured specimens differ from those of PA. erispata. 
As the other fragments and imperfect small specimens, of which I have many, 
uniformly maintain the characters above referred to, the species seems to differ from 
any other known to me, and IJ have accordingly proposed for it the above name. 
