174 CRETACEOUS LAMELLIBRANCHIA. 
ficured as P. elongatus by @Orbigny appears to belong to another species. P. 
obliquus, Sowerby, is probably identical with P. elongatus ; the type, however, is 
missing, and the figures do not show the character of the ornamentation satis- 
factorily, but it is clear from the description that the ribs were in triplets and 
covered with numerous scales. 
This is a moderately common species in the Upper Greensand and Lower 
Chalk. In a specimen from the Chalk Marl of Ventnor (Pl. XXXI, fig. 12) 
the shell is proportionately higher, and has a smaller apical angle than usual ; 
it is near to the form figured by Geimitz (1872, pl. xliv, figs. 2, 3). Other 
specimens connect this high form with those of normal proportions. A few 
specimens from the Lower Greensand of Upware—now in the Woodwardian 
Museum, and in Mr. J. F. Walker’s collection, were referred by W. Keeping to 
P. Raulinianus ; their state of preservation is less satisfactory than that of Upper 
Cretaceous examples, but they approach closely some forms of P. elongatus from 
the Upper Greensand and Chalk, and are probably correctly referred to that 
species. 
Types.—The type of P. elongatus came from the Cenomanian of Le Mans. 
The type of P. obliquus from the Upper Greensand (? Devizes) cannot be found in 
the Sowerby collection. The types of P. Raulinianus came from the Albian of Grand 
Pré and Machéroménil (Meuse). 
Distribution—Gault of Folkestone (zones vill and xi of Price). Cambridge 
Greensand. Upper Greensand of Ventnor. Malmstone of Alton. Chloritic Marl 
of Maiden Bradley. Rye Hill Sand of Warminster. Chalk Marl of Ventnor, 
Folkestone, and Burwell. Totternhoe Stone (//. subglobosus zone) of Arlesey and 
&< 
Burwell. Lower Greensand of Upware (see ‘ Remarks” above). 
Precren (Cutamys) crerosus, Defrance, 1822. Plate XXXII, figs. 4 a—ua, 5 a,b, 
6 a—c; Plate XXXITI. 
1822. Prcren crerosus, Defrance. A. Brongniart. Descript. géol. Envir. de 
Paris (in Cuvier’s Ossem. foss., vol. 11), 
pp. 251, 598, pl. in, fig. 7. 
— —  aracunorpes, Defrance. Brongniart. Tbid., pp. 251, 599, pl. i, 
fie. 8. 
— —  witipa, G. Mantell. Foss. S. Downs, p. 202, pl. xxvi, figs. 4, 9 
(? fig. 1). 
1823. — nitipus, J. de C. Sowerby. Min. Conch., vol. iv, p. 120, pl. ecexeiv, 
home 
1825. — cretosus, Defrance. Dict. Sci. nat., vol. xxxviii, p. 267. 
— — ARACHNOIDES, De/rance. Ibid., p. 266. 
