66 CRETACEOUS LAMELLIBRANCHIA. 



whole forms a rectangular network, with pits at the intersection of the grooves. 

 Teeth numerous. Margins of valves smooth. 



Measurements : 











Length . 



(i) 



25 



(2) 



20 





(3) 



15 - 5 mm 



Height . 



21-5 . 



18 





13 



Thickness 



21 



17-5 . 





11 „ 



(1) and (3) 



from Ball Wood. 



(2) from Maiden 



Brad 



ley. 



Ti/pes. — From the Cenomanian of Rouen. 



Distribution. — Chloritic Marl of Ball Wood, near Plush, and of Maiden Bradley. 

 Base of. Chalk Marl (zone of Schlcenbaehia various) of Cerne, near Chard. 



Genus — Pectunculus, Lamarck, 1799. * 

 [' Mem. Soc. Hist. Nat. Paris,' p. 87.] 



1. Lower Cretaceous Species. 



Pecttjnctjlus makullensis, Leymerie, 1842. Plate XIII, figs. 9 a — c, 10. 



18J2. Pectunculus marullensis, A. Leymerie. Mem. Soc. G-eol. de Prance, 



vol. v, p. 7, pi. ix, fig. 2. 

 1841. --• — A. cTOrbigny. Pal. Franc. Terr. Cret., vol. iii, 



p. 187, pi. cccvi, figs. 1—6. 

 1848. — marollensis, H. Q. Bronn. Index Palseont., vol. i, p. 938. 



1850. — makullensis, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 80. 



? ? 1883. — — W. Keeping. Foss., &c, Upware and Brick- 



hill, p. 116, pi. v, fig. 11. 



Description. — Shell of moderate size, suboval or nearly orbicular, longer than 

 high, rather convex, compressed antero-dorsally and. postero-dorsally. Anterior 

 margin rounded, posterior slightly sub truncate. Umbones of moderate size, 

 close together, nearly median. Hinge-area small. Hinge with from four to six 

 oblique teeth on each side. Ornamentation consists of numerous radial ribs, which 

 bear finer ribs, and are crossed by fine concentric ribs. 



Measurements : 



(i) (2) 



Length . . . 12*5 . . 11 mm. 



Height ... 11 . 9-5 „ 



(1) and (2) from Shankliu. 

 1 Dall considers that the name Qlycimeris, Da Costa, should be adopted in place of Pectunculus 

 or Aximea. Until the necessity for this change has been definitely shown, I prefer to retain the name 

 which has been in general use for the last hundred years. Dall, ' Trans. Wagner Free Inst. Sci. 

 Philadelphia,' vol. ii, pt. iv (1898), pp. 571, 607. Cossman, 'Eev. Crit. Paleozool.' (1899), p. HG. 



