PROSOBRANCHIATA. 347 
No. 269. Nzrivina tristis, Forbes. Tab. XXXIV, fig. 12 a, 4. 
NeERITINA TRISTIS, Forbes. Mem. Geol. Surv. Isle of Wight, p. 46, 1856. 
= — J.W. Lowry. Chart Brit. Foss., pl. ii, 1866. 
Spec. Char. N. Testd fuscd, ovato-oblongd, tenui, spird brevi, obtusd, anfractibus 
tribus, ultimo magno, apertura magnd semilunari, columella pland margine simplict, labro 
acuto, edentulo. 
Diameter, 33;ths of an inch. 
Locality. empstead (Forbes). 
A few specimens were many years ago given to me by the late Edward Forbes with 
the above specific name attached. These appear to differ from JV. concava in having a 
rather less elevated spire and a slight depression round the upper part of the volution, 
as in concava; but I can discover no angularity in the volutions. It is of a umform 
sombre or brownish colour, from which I presume it received its name. ‘This has not 
been figured in the ‘Geol. Survey Memoir,’ but it is very well represented by Mr. 
Lowry in his ‘Illustrations of British Fossils’ above referred to. Forbes described it 
(‘ Memoir Geol. Survey,’ p. 46) as “a small globose shell, with volutions rather angulated ; 
aperture semilunate, inner lip obscurely denticulated, surface smooth without ornamen- 
tation.” 
No. 270. Neritina aperta, J. Sowerby. Tab. XXXIV, fig. 20 a, 6. 
Nerita aperta, J. Sow. Min. Conch., t. eecexxiv, figs. 2, 3, 4, 1823. 
= — Morris. Catal. Brit. Foss., 2nd edit., p. 264, 1854. 
— — J. Lowry. Chart Brit. Tert. Foss., pl. ii, 1866: 
Nerivina (Mirruxa) areria, Sand. Land- und Siissw.-Conch., p. 269, t. xv, figs. 
15, 15 a, 1872. 
Spec. Char. NV. Testd subglobosd, apice depresso, viv conspicuo ; anfractibus 2—3 ; 
lineis tenuibus ornatd ; aperturd semilunari; margine dextro, acuto ; columella pland, 
margine acuto, in medio minute denticulatd, posteriore unidentatd. 
Height, + of an inch; diameter, ths of an inch. 
Localities. Colwell Bay (J. Sowerby), Headon Hill, Milford (S. Wood). 
The shell figured by Sowerby as above referred to is a good representation of a small 
specimen of this species, which is not rare in the Upper Eocene of Hampshire and the 
Isle of Wight. I have not, however, seen any so small as those represented in figures 3 
and 4 of tab. 424 of ‘ Min. Conch.,’? which, no doubt, were immature specimens. The 
ornamentation is variable, as pointed out by Mr. Sowerby, and the shells have more or 
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