170 CRETACEOUS LAMELLIBRANCHIA. 
Left valve a little more convex, with similar ornamentation; ears shehtly 
unequal. 
Measurements : 
(a) (2) (3) 
Leneth : 37 : 34 : 24 mm. 
Height : AY 43 Sie 
(1) Greensand, Haldon. 
(2,3) Chalk Marl (Bed 11), Dunscomhe. 
Affinities. —P. acuminatus, Geinitz,’ resembles closely this species, but seems to 
differ from it in having few or no scaly spines on the ribs, and also m having the 
concentric ornament somewhat coarser; the ribs, as a rule, are also less sharp and 
somewhat less numerous. The state of preservation of the spines in 1’. subacutus 
varies a good deal in different specimens; in some cases (as in fig. 8) they are 
absent from the greater part of the surface. It seems probable, therefore, that the 
comparison of good series of specimens might show P. aeuminatus and P. subacutus 
to be identical. 
The form from the Cambridge Greensand, referred to this species by Jukes- 
Browne, possesses the characteristic concentric ornamentation, but has rather more 
numerous ribs; only three specimens have been seen, and since they are rather 
imperfectly preserved, the determination of the species cannot be regarded as quite 
certain. 
T'ype.—From the Cenomanian of Le Mans. 
Distribution.—Cenomanian :—Bed 10 of Hooken, Beds 11 and 12 of Dunscombe, 
Bed 12 of Branscombe. Greensand of Haldon. ? Cambridge Greensand. 
Prcren (Cutamys) ELoNGATUS, Lamarck, 1819. Plate XXXI, figs. 10, 11 a,b, 12,6, 
13; Plate XXXII, figs. Lazb; 
Pony 83 Gly 
1819. Precren eLoneatus, Lamarck. Anim. sans Vert., vol. vi, p. 181. 
1822. —  osxiquus, J. de C. Sowerby. Min. Conch., vol. iv, p. 95, pl. ccelxx, 
fig. 2. 
1 Geinitz, ‘Char. d. Schicht. u. Petref. des sichs-bohm. Kreidegel.,’ pt. 3 (1842), p, 84, pl. xxi, 
fiz. 6; Reuss, ‘Die Verstein. der bohm. Kreidvformat.,’ pt. 2 (1846), p. 29, pl. xxxix, figs. 20, 21; 
VArchiac, ‘Mém. Soe. géol. de France,’ ser. 2, vol. 11 (1847), p. 309, pl. xvi, fig. 8; Kunth, ‘Zeitschr. 
d. deutsch. geol. Gesellsch.,’ vol. xv (1863), p. 725; Michael, ibid., vol. xlv (1895), p. 285; Romer, 
‘Geol. v. Oberschles.’ (1870), p. 833, pl. xxvi, fig. 3; Geinitz, “ Das Elbthalgeb. in Sachsen” (‘ Paleeonto- 
eraphica,’ vol. xx, pt. 1, 1872), p. 194, pl. xliii, fig. 16; pl. xliv, fig. 1; Fritsch, ‘ Bohm. Kreideformat. 
III. Iserschicht.’ (1883), p. 116, fig. 89; Notling, “ Die Fauna d. baltisch. Cenoman.” (‘ Palaeont. 
Abhandl., vol. ii, 1885), p. 19, pl. iii, fig. 2; Leonhard, “ Die Kreideformat. in Oberschles.” (‘ Palaonto- 
graphica,’ vol xliv, 1897), p. 26. 
