LIMA. 



15 



Measurements 



(i) (2) (3) (4) (5) 



Length .32 31 . 29 . 29 23 mm. 



Height . 33 . 32 . 29 . 26 . 23 

 (1, 2) Upper Greensand, Potterne. 

 (3, 5) Ventnor. 



(4) Blackdown. 



Affinities. This species is distinguished by its compressed valves and rounded 

 outline. 



Type. From the Cenomanian of Le Mans. 



Distribution. Upper Greensand (zone of Schlcenbachia rostrata) of Potterne 

 (Devizes) and Blackdown. Upper Greensand (zone of Pecten asper) of Ventnor. 

 Chalk Marl of Folkestone. 



LIMA (PLAGIOSTOMA) MJSTEBI, sp. nov. Plate IV, figs. 2,3. Text-fig. 4. 



1896. LIMA SIMPLEX, A. J. Jukes-Browne. Quart. Journ. Geol. Soc., vol. lii, p. 152. 



Description. Shell ovate or subtrigonal, much compressed, a little higher than 

 long, oblique, considerably inequilateral; antero-dorsal margin long and 



FIG. 4. Lima (Plagiostoma) Meyeri, sp. nov. Upper Greensand, Warminster. Museum of Practical Geology, 

 No. 8838. Left valve and antero-dorsal view. Natural size. 



straightened, ventral and postero-ventral margins rounded. Umbones small, close 

 together. Apical angle from 90 to 100. Anterior area depressed, long and 

 narrow, with a few radial ribs and vertical grooves. Posterior ear small ; anterior 

 ear not seen. 



Ornamentation consists of narrow, linear, shallow, pitted grooves which may 



