CUCULLjEA. 61 



Cuoulljsa obesa (Pictet and Rom',), 1852. Plate XII, figs. 6, 7 a, b, 8 a, b. 



1852. Aeca obesa, F. J. Pictet and W. Boux (non Soioerby). Moll. Foss. Gris 

 verts de Geneve, p. 464, pi. xxxviii, figs. 1, 2. 



1866. — — F. J. Pictet and G. Campiche. Foss. du Terr. Cret. de Ste. 

 Croix (Mater. Pal. Suisse, ser. 4), pt. 3, p. 459. 



1871. — — F. Stoliczka. Palaeont. Iudica, Cret. Fauna 8. India, vol. iii, 

 p. 343 (Trigonoarca?). 



Non 1833. Aeca obesa, G. B. Sowerby. Proc. Zool. Soc, pt. 1, p. 21 (figured Beeve, 

 Conch. Iconica, vol. ii, 1843, pi. i, fig. 3). 



Description. — Shell subrhomboidal, rounded, a little inequilateral and oblique, 

 much inflated. Posterior border slightly convex, forming an obtuse angle with 

 the hinge-line, and joining the ventral border at an acute but rounded angle. 

 Umbones prominent, well separated except in young forms. A prominent but 

 rounded carina extends from the umbo to the postero- ventral angle. Hinge-area 

 long, of moderate breadth, with numerous (often thirteen to eighteen) closely-set 

 ligament-grooves. Ornamentation consists of faintly marked radial ribs crossed 

 by lines of growth. Hinge with some central transverse teeth, and lateral teeth 

 which are parallel or nearly parallel to the hinge-line. Posterior adductor plate 

 well marked. 



Measurements : 



Length 

 Height . 

 Thickness 

 Hinge-line 



Affinities. — This is related to C. glabra, Sowerby, but can be distinguished 

 from that by its more inflated form, more prominent umbones, more rounded 

 outline ; the ventral margin is placed more obliquely with regard to the hinge- 

 line ; the hinge-line is relatively shorter and the ligament-grooves more numerous ; 

 the radial ribs are less distinctly marked. 



Remarks. — The name Area obesa was pre-occupied by Sowerby for a recent 

 species dredged near the coast of West Columbia ; but since the fossil form is now 

 referred to the genus Cuadlsea the specific name may be retained. 

 Types. — The types are from the Gault of the Perte du Rhone. 

 Distribution. — Gault of Folkestone (zones viii, ix) ; and Aylesford. Cambridge 

 Greensand (derived). Chloritic Marl of the Isle of Wight and Warminster. 

 Upper Greensand of Devizes. 



(1) 



53 



(2) 



47 



(3) 



43 



(4) 



28 



(5) 



22 mm 



48 



42-5 



40 



25-5 



18 „ 



52 



44 



37 



21 



17 „ 



39 



31 



26 



15 



14 „ 



