EXPLANATION OF THE PLATES. XV 



PLATE V. BIVALVE MOLLUSCANS. 



Page 



FIG. 1 . Solen Siliqua 240 



a. The foot. b. The shell. 



N.B. The two figures in outline shew varia- 

 tions in shape assumed by the foot, under 

 different circumstances. 



2. Anomia Cepa 262 



a. The tendon, b. The aperture of the upper 



valve through which it passes. 



3. Anomia Ephippium. 

 a. Aperture. 



4. Terebratula 263 



a. Aperture of the lower valve through which 



the tendon passes. 



5. Trigonia margaritacea 264 



a. Foot formed for leaping. 



b. b. b. Valves of the shell. 



PTEROPOD AND HETEROPOD MOLLUSCANS. 



6. Cliodites fusiformis "j 



7. Polycera capensis ^ 



OA1 



8. Pterotrachea rufa } 



PLATE VI. UNIVALVE MOLLUSCANS. 



FIG. 1. Voluta athiopica, to shew the animal 282 



a. The eye, shewing iris and pupil. 



b. The right hand tentacle. 



c. The proboscis exserted. 



d. The frontal margin of the head. 



e. The respiratory tube or siphuncle. 



f. Appendage at its base. Analogous to the 

 crus infundityjli in Nautilus ? ' Owen. 



g. g. The two gills, of which the right hand one 

 has but one series of laminae. 



h. Termination of the alimentary canal. 



1 Owen's Mem. on Naut. Pampil. t. v. h. 



