SUPPLEMENT TO THE BIVALVIA. 13 
Spec. Char. C. Testa levi, convexd, subtrigond, margine antico vie producto, margine 
postico angulato, subproducto, margine ventrali rotundato.” ( Morris.) 
Length, Yeths of an inch ; heeght, 3 an inch. 
Localities. Bembridge, Hempstead (Fordes). 
There is a considerable difference in the form of this shell from (C. odovata, on 
which account I have kept it specifically distinct. A large series of each, however, 
might possibly remove the distinction and unite this with oJovata. My specimens show 
a more rounded form than odovata, with a much depressed umbo and an absence of the 
strongly angular form of the posterior side of that shell. They are also less triangular 
and not so inflated. The species has been kept distinct by Messrs. Forbes and Morris, 
and I have thought it best to follow them in so doing. 
The specimens of this species have undergone considerable erosion of the umbones, 
so much so that a specimen which I have had represented shows the cardinal teeth 
standing out prominently, and these are visible even when looking at the exterior of the 
shell. 
17. Cyrena pererpita, Zam. Tab. B, fig. 10 a—d. 
CycLas DEPERDITA, Lam. Ann. du Mus,, t. vil, p. 425, 1803. 
CYRENA _ Desh. Coq. Foss. des Env. de Par., p. 118, pl. xix, figs. 14, 15, 
1824, 
— — S. Wood. Lond. Geol. Journ., p. 118, 1847. 
— — Morris. Mem. Geol. Surv. (Isle of Wight), p. 156, pl. vii, fig. 
11 a, 6, 1856. 
— — Lowry. Chart Brit. Tert. Foss., pl. ii, 1866. 
— — Sandberger. Jand- und Sussw.-Conch., p. 251, t. xiv, fig. 3, 1872. 
Spec. Char. ‘*C. Testa ovato-ventricosd, obliqua, subtrigond, levigata substriatave ; 
umbonibus magnis, inflatis, recurvis ; dentibus cardinalibus tribus valvd sinistrd, duobus 
dextra ; dentibus lateralibus subaqualibus, levigatis.” (Desh) 
Length, 3ths of an inch; eight, ~7sths of an inch. 
Localities. Britain: Hordle, Headon Hill (Worrzs). 
France: Pontoise (Deshayes). 
This is an abundant shell at Hordle in the purely freshwater deposit at the cliff of 
that locality, in association with the remains of the Alligator,’ Crocodile, Trionyx, Emys, 
Lepidosteus, and sundry Mammalia, as mentioned by me in the ‘ Lond. Geol. Journ.’ 
(1846), p. 6. 
1 All the vertebrate remains obtained by me from Hordle (which included many besides those figured 
in the ‘London Geological Journal,’ and among them the hitherto undescribed jaw of a Rodent and a 
bone of a Bird) were given by me to the National Collection in the British Museum in 1846, 
