412 



CRETACEOUS LAMELLIBRANCHIA. 



their relationship. Hennig also includes E. auricular is (Wahlenberg) 1 in E. halio- 

 toidea. 



Pictet and Campiche figure and describe examples of E. conica from the Aptian. 

 Specimens of Exogyra from the Lower Greensand of Upware, Brickhill, Faringdon 

 and Shanklin have been referred to E. conica ; in these the carina is more rounded 



233 



Figs. 232— 242. — Exogyra conica (Sow.). Sedgwick Museum except 238— 240. 232— 235, Cambridge 

 Greensand (base of Chalk Marl). 233, 234, left valves. 232, right valve of 233. 235, right valve 

 of 234. 236, 237, zone of Holaster subglobosus, Burwell ; 236, light valve ; 237, anterior view of 236 

 showing the large size of the attached surface of the left valve. 238, 239, Gault, Folkestone ; 

 Museum of Practical Geology, No. 20873 ; 238, right valve ; 239, anterior view showing left valve 

 attached to a flat Inoceramus. 240, Upper Greensand, Devizes. Museum of Practical Geology, 

 No. 20999. Left valve. 241, 242, Cambridge Greensand ; ribbed form with a large surface of 

 attachment ; 241, left valve; 242, anterior view of 241. All natural size. 



than in the common form of the species, but they agree closely with, and seem to 

 be inseparable from some forms of E. conica from the Upper Greensand (figs. 

 215—218). 



Small specimens with radial ribs (fig. 219), such as the one figured by Goldfuss 



1 'Petrific. tell. Suec' (1821), p. 58. See also Schroder, ' Zeitschr. d. deutsch. geol. Gesellsch.,' vol. 

 xxxiv (1882), p. 260, pi. xv, fig. 4. 



