PLATE XLYII. 



Pigs, 1 — 2. OsTREA [Alecteyonia] diluviana, Linne, p. 466; 1, a lower valve, with un- 



equal sharp ribsj the median one the largest ; 2, upper valve ; near Serdamnti- 

 galum, Tricldnopoly gronp. 



pjo's. 3 — 4. OsTREA [Alectryonia] tngulata, &///o(!/^., p. 470; 3, inner-view of an upper 



valve ; 4, back-view of an upper valve with the terminal portion detached ; 

 4 a,* posterior-view of the larger portion of fig. 4 ; Ootacod, Arrialoor group. 



Figs. 5 — 7. PlicatCla SESSILIS, Stol., p. 446; 5 and 6, views of lower or attached valves, 



with the shell surface mostly well preserved ; from near Moraviatoor ; 7, view 

 of lower valve and of the posterior side of a specimen with the shell-surface 

 nearly entirely worn off; from Oofatoor, Ooiatoor group. 



* Referred to in the text on p. 470 as fig. 5. 



