PLATE VI. 



Genus Arca, Lamarck. 



FIGS. 



1—3. A. Dupiniana, d'Orb. (P. 32.) 



1,2. Pema-bed, Atherfield. Leckenby Collection. Woodwardian Museum. 1 a, right 

 valve; lb, dorsal view of same specimen ; 2, hinge of left valve x 1|. 



3. Ferruginous Sands, Shanklin. Collection of C.J. A. Meyer. Ornamentation on 

 the right valve near the ventral margin below the umbones x 3. 



4, 5. A. Garteroni, d'Orb. (P. 33.) 



i. Lower Greensand, Upwa re. Woodwardian Museum, a, left valve; b, anterior 

 view ; c, dorsal of same specimen. Figured by Keeping. 



5. Atherfield Beds, East Shalford. Collection of C. J. A. Meyer, a, left valve; 

 b, hinge and area of same x li ; c, ornamentation, from the auterior part of 

 the valve, x 3. 



6, 7. A. SoMctse-Orucis, Pict. and Camp. Lower Greensand, Upware. 

 Woodwardian Museum. (P. 34.) 



(5. a, left valve ; b, outline of anterior end ; c, dorsal view of same specimen. (The 

 right umbo and the auterior part of the area are partly obscured by adhering 

 rock.) 



7. a, right valve ; b, dorsal view of same specimen ; e, ornamentation x 2. 



Genus Barbatia, Gray. 



8, 9. B. aptiansis (d'Orb.). Crackers, Atherfield. Leckenby Collection, 

 Woodwardian Museum. (P. 35.) 



8. a, left valve ; b, dorsal ; c, right valve ; d, anterior ; e, part of left valve near the 



mid-ventral margin x 3. 

 Si. a, left valve; b, right valve. 



