238 CRETACEOUS LAMELLIBRANCHIA. 
Kamily—ANATINIDA, Gray. 
Genus—Puxrcromya, P. de Loriol, 1868. 
(De Loriol and Cotteau, ‘Mon. Paléont. Géol. Portlandien de l'Yonne,’ p. 89.) 
PLECTOMYA ANGLICA, sp. nov. Plate XX XIX, fig. la, b. 
Description.—Shell elongate-oval, slightly inequilateral, compressed ; anterior 
and posterior ends rounded; ventral margin slightly convex. Umbones broad, 
with a slight posterior curvature. 
The part of the shell in front of a line drawn from the umbo to the opposite 
ventral margin is ornamented with strong concentric ribs separated by broad 
furrows; these ribs become nearly or quite obsolete on the posterior middle part 
of the shell (except near the umbo), but re-appear on the postero-dorsal part. 
The entire surface of the shell is ornamented with numerous radial rows of 
granules. Length 49 mm.; height 27 mm. 
Affinities—This species is similar in general character to Plectomya Agassizi 
(VOrbigny'), but the shell is less elongate, the ribs on the anterior part of the 
shell cut the margin and the growth-lines obliquely, and on the posterior median 
part the ribs are almost obsolete. It also shows some resemblance to P. Rhodani 
(Pictet and Roux’). 
Remarks.—Ot this species I have seen only two examples, neither of which 
shows the interior, so that I am unable to express an opinion as to affinities of the 
genus Plectomya. 
Distribution. —Lower Greensand (Crackers) of Atherfield.’ 
Genus—ANAtTINA, Lamarck, 1809. 
(‘ Philosoph. Zool.,’ vol. i, p. 319; ‘ Hist. nat. Anim. sans Vert.,’ vol. v, 1818, p. 462.) 
Sub-genus—Crroomya, L. Agassiz, 1842. 
(‘ Etudes crit. Moll. Foss.,’ Myes, p. 143.) 
1<Pal. Franc. Terr. Crét.,’ vol. iii (1845), p. 371, pl. ecclxix, figs. 1,2; Pictet and Campiche, 
‘Foss. Terr. Crét. Ste. Croix’ (‘ Matér. Pal. Suisse,’ ser. 4, 1865), p. 99, pl. evil, fig. 1. 
2 «Moll. Foss. Grés verts de Genéve’ (1852), p. 410, pl. xxix, fig. 4. 
% An imperfect specimen from the Lower Greensand of Atherfield is probably an example of 
Plectomya marullensis (d’Orbigny), op. cit., p. 376, pl. ccclxxi, figs. 3, 4; Pictet and Campiche, op. cit., 
p. 101, pl. evii, figs. 2, 3. 
