on the Genera Orbicula and Crania of Lamarck. 4J3 



REFERENCES to the accompanying FIGURES. 



Tab. XXVI. 



Fig. 1. Orbicula ljevis. 



a. Attached to a grey flint pebble, which is nearly coated by the 



root of an Isis. 



b. Another view, to show the elevation. 



c. Inside of the upper valve, showing the two fringed arms. 



d. Inside of the lower valve. 



Fig. 2. Orbicula norvegica. 



a. A very young specimen. 



b. A full grown one. 



c. Specimen showing the fringed arms extended like rays beyond 



the shell. 



d. Inside of the upper valve. 



e. Inside of the lower valve. 

 f. Under part of lower valve. 



Fie. 3. Crania personata. 



* ° 



a. Piece of sandstone, with several specimens of various sizes 



attached to it, from Orkney. 



b. Inside of the upper valve, do. 



c. Inside of the lower valve, do. 



d. Ditto, with the dried animal, do. 



e. Inside of a lower valve, from the Mediterranean. 



Fig. 4. Crania antiqua. 

 a. Outside of upper valve, b. Inside of do. 

 c. Inside of lower valve. 



XXIII. A Com- 



