98 EOCENE MOLLUSCA. 
4. Pecruncutus GLososus, J. Sowerby. Tab. XVI, fig. 9. 
PrcTtuNcULUS GLoBosus. J. Sow. in Dixon’s Geol. of Sussex, p. 170, t. 3, fig. 20, 1850. 
Spec. Char. P. testé crassd orbiculari, globosd, sub-equilaterali, equivalvi, levigatd, 
aut obsolete radiatd ; margine cardinali arcuatd, umbonibus prominentibus, marginibus 
crenulatis. 
Shell thick, obliquely orbicular, globose, slightly inequilateral, equivalve, smooth, with 
faint or obsolete radiations; hinge or dental area curved ; beaks prominent; margins 
crenulated. 
Diameter, 1 inch. 
Locality. Bracklesham (Dizon). 
This appears to be more tumid at the upper part than any other species. There is 
a resemblance between it and proximus, which is common at Barton; but that shell is 
always more or less oblique, with a sharper or Jess tumid umbonal region, and this shell, 
as its name implies, is more globose. 
d. PectuncuLtus Puiumsreapiensis, J. Sowerby. Tab. XVI, fig. 6, a, d. 
PecTUNCULUS PLUMSTEADIENSIS. J. Sow. Min. Con., t. 27, fig. 3, 1813. 
— — Morris. Catal. Brit. Foss. ae 219, 1854. 
Spec. Char. P. testa tenui, lenticulart vel orbiculato-subquadrata, equilaterali ; 
obsolete costatd vel radiata, concentrice striata ; umbonibus depressis ; marginibus crenulatis ; 
ared connexus parvd. 
Shell thin, lenticular, with a somewhat roundedly quadrangular outline; equilateral, 
obsoletely costated or radiated; beaks depressed, with a small area for the connector ; 
margins toothed. 
Diameter, 14 inch. 
Localities. Plumstead; Upnor; Katesgrove, near Reading. 
This is thinner than the generality of the genus, and the rays upon the exterior are 
broad and rounded; it resembles drevirostris in having a small beak, but that shell is 
more oblique, with the rays less prominent, the hinge less curved, and the denticles fewer. 
Tn the ‘ Geol. Journ.,’ vol. x, p. 120, 1854, this species and drevirostris are united with 
P. terebratularis, Lamarck. M. Deshayes (p. 852) considers the two latter as distinct, 
and I am disposed to agree with him, but I believe also that the above-named P/um- 
steadiensis is entitled to a distinct specific position. 
