16 CRETACEOUS LAMELLIBRANCHIA. 



be confined to the anterior and posterior parts of the valves or may extend over 

 the whole surface. The grooves are somewhat irregular and the interspaces are 

 broad and flattened. At distant intervals a few well-marked growth-rings occur, 

 beyond which, in some cases, the ribs cease. 

 Measurements : 



(1) (2) (3) (4) (5) 



Length . 69 . 53 . 48 . 42 . 34 mm. 

 Height .71 . 56 . 52 . 47 . . " 37 



(1 5) Upper Greensand, Warminster. 



Affinities. This species differs from Lima semiornata (p. 14) in being larger, 

 relatively higher, more trigonal in outline, and in having the radial grooves more 

 extensively developed. It is distinguished from Lima simplex, d'Orbigny, 1 in 

 being much less convex, in the height being relatively less, the antero-dorsal 

 margin shorter, the anterior area smaller, and the anterior grooves less prominent. 



The shell is relatively longer and the apical angle larger than in L. sub-conso- 

 brina, d'Orbigny. 2 It is also relatively longer, with a longer antero-dorsal margin 

 and the radial grooves less well developed, than in L. cretacea (p. 22). 



Types. From Warminster. In the Museum of Practical Geology. 



Distribution. Upper Greensand (zone of Pecten asper) of Warminster. Rye 

 Hill Sands and Chloritic Marl of Maiden Bradley. Cenomanian (Meyer's Beds 10 

 and 11) of Hooken and Dunscombe (Devon coast). 



LIMA (PLACIOSTOMA) GLOBOSA (Smoerly), 1836. Plate IV, figs. 4 a c, 5 a, />, 6 a c. 



1836. LTTCINA? GLOBOSA, J. de C. Sowerby. Trans. Geol. Soc., ser. 2, vol. iv, 



p. 335, pi. xi, fig. 2 (non Lucina 

 globosa, Homer, 1839). 



1854. LIMA GLOBOSA. /. Morris. Cat. Brit. Foss., ed. 2, p. 171. 

 1895. E. Tiessen. Zeitschr. der deutsch. geol. Gesellsch., vol. 



xlvii, p. 473. 



Description. Shell very convex, of moderate size, oval, length considerably 

 greater than height, outline rounded with the antero-dorsal margin long and 

 straightened. Umbones incurved, blunt. Apical angle about 118. Anterior 

 area large, very deep, limited by a sharp edge, with radial ribs. Ears small. 



Surface of valves polished, with faintly-marked growth-lines at intervals; 



1 'Pal. Fran9. Terr. Cret.,' vol. iii (1847), p. 545, pi. ccccxviii, figs. 5 7. 



2 Ibid., p. 556, pi. ccccxxii, figs. 4 7 ; L. sub-consobrina, d'Orbigny, ' Prodr. de Paleont.,' vol. ii 

 (1850), p. 167. 



