412 



CRETACEOUS LAMELl.IBRANCHIA. 



their velationsliip. Hennig also includes E.auricnlitris (Walilenberg)' in E. halio- 

 tot'dea. 



Pictet and Campiclie figure and describe exam^^les of E. conica from the Aptian. 

 Specimens of E.ro/ii/rn fi'om the Lower Greensand of Upware, Brickhill, Faringdon 

 and Slianklin have becMi referred to H. conica; in these the carina is more rounded 



233 



239 



Figs. 232—242. — Exoqyra conica (?to\\\). Sedf^wkk Museum oxeept 23S— 240. 232—235, Cambridge 

 Greensand (base of Chalk Marl). 233, 231-, loft valves. 232. rifjbt valve of 233. 23.5, rifrht valve 

 of 234. 23(), 237, zone of Holaster xubglubosus, Burwell ; 230, right valve : 237, anterior view of 236 

 showin-j the large size of the attached surface of the left valve. 238, 239, Gault, Folkestone ; 

 Museum of Praitical Ueology, No. 20873 ; 238, right valve ; 239, anterior view showing left valve 

 attached to a flat Inoccramus. 240, Upper Greensand, Devizes. Museum of Practical Geolog>', 

 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 thej agree closely with, and seem to 

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

 215-218). 



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



^ 'Petrific. tell. Suec' (1821), p. 58. See also Schroder, ' Zeitscbr. d. deutsdi. gcol. Gesellscli.,' vol. 

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



