50 CRETACEOUS LAMELLIBRANCHIA. 
Affinities.—Cucullea Forbesi is closely related to OC. Gabrielis, Leymerie,' but 
differs from it in the presence of strong radial ribs on the adult shell. In C. 
Gabrielis (of which I have seen three or four very perfect specimens) these ribs 
are found on the young parts only, and are but faintly marked. Cucullea tumida, 
Matheron, is perhaps related to C. Forbesi; it was founded on an internal cast. 
C. Forbesi is distinguished from Arca Moreana, d’Orbigny,’ by its strong carina 
and more widely separated umbones. 
The form figured by Coquand® as Arca dilatata (from the Aptian of Obon, 
Arcaine, &c.) is very near to C. Forbesi; but the shell is longer posteriorly, and 
the radial ribs are not seen. A. Gresslyi, de Loriol,* is, perhaps, closely allied to 
CO. Forbesi, but is at present imperfectly known. 
Types.—From Atherfield. I have not seen the original of Forbes’ figure 
(1845). 
Distribution.—Perna-bed of Atherfield. Also, according to Fitton, in Beds iii, 
vi, ix, and xiii of Atherfield. 
Cucunnma Cornvettana (d’Orbigny), 1844. Plate VIII, figs. 11—13; Plate X, 
figs. 1 a—e, 2a, b, 3. 
1844, Arca Cornvetiana, A. d’Orbigny. Pal. Frang. Terr. Crét., vol. ii, p. 208, 
pl. ceexi, figs. 1—3. 
1845. — _— E. Forbes. Quart. Journ. Geol. Soe., vol. i, p. 246. 
1850. — — A. d’Orbigny. Prodr. de Pal., vol. ii, p. 80. 
1854. — — J. Morris. Cat. Brit. Foss., ed. 2, p. 185. 
1855. — _ G. Cotteau. Moll. Foss. de l'Yonne, p. 86. 
186]. — —_ P. de Loriol. Anim. Invert. Foss. du Mont Saléve, 
p. 86, pl. x, fig. 7. 
1866. — _— F. J. Pictet and G. Campiche. Foss. Terr. Cret. de 
Ste. Croix (Matér. Pal. Suisse, ser. 4), pt. 3, 
pp- 445, 469. 
1867. — - P. de Loriol. In A. Favre, Recherch. géol. dans 
Savoie, &e., vol. i, p. 380, pl. ¢, fig. 9 
1871. — -- F. Stoliczka. Palwont. Indica, Cret. Fauna 8. India, 
vol. il, p. 842 (? Trigonoarca). 
21883. Cucunnma suBNANA, W. Keeping. Foss., &c., Upware and Brickhill, p.115 
pl. v, fig. 10. 
1«Mém. Soe. Géol. de France,’ vol. v (1842), p- 6, pl. vii, fig. 5; d’ One Pal. Frang. Terr, 
Crét.,’ vol. iii (1844), p. 198, pl. ceeviii. 
2 D’Orbigny, ibid., p. 200, pl. eecix, figs. 1—3. 
5 Mon. de l’étage Aptien de l’Rspagne ’ (1865), p. 189, pl. xxii, figs. 1, 2. 
4 Anim. Invert. foss. Néoc. du Mt. Saléve’ (1861), p. 87, pl. xi, figs. 1—8. 
