10 PROCEEDINGS OF THE ACADEMY OF [Jan., 



Plate I. — Fig. 1. — Median tooth of Fulgur carica (unused). 

 Fig. 2. — ^Aledian tooth of Fulgur carica (worn). 

 Fig. 3. — Median tooth of Urosaiphinx (unworn). 

 Fig. 4. — Median tooth of Urosaiphinx (worn). 

 Fig. 5. Sycolypus eating an oyster viewed from above. 



Fig. 6. — Sycotypus eating an oyster viewed from side. Tlie oyster had had 

 the end toward the conch broken for about f inch. 



Plate II. — Fig. 7. — Sycotypus on top of oyster (semi-diagrammatic). 



Fig. 8. — The same a few seconds afterward, showing the margin of the Sycoty- 

 pus shell wedging apart the shells of the oyster. 

 Fig. 9. — Sycotypus wedging apart the valves of an oyster. 



Plate III. — Fig. 10. — Sycotypus in search of food. 

 Fig. 11. — Sycotypus eating Mya. 



Plate IV. — Fig. 12. — Sycotypus eating Mya. 



Fig. 13. — F. carica eating Venus, showing how it holds the shell. 



Plate V. — Diagrams illustrating the wanderings of F. perversa, F. carica and S. 

 canaliculatus during a period of six weeks. Each square of the diagram 

 represents one square foot. Each of the diagrams represent an aquarium 

 of salt water five feet by eleven feet. The plottings w^ere made daily. 

 The Roman numerals indicate the identification number of the in- 

 dividual welks. Arabic numerals indicate days at one spot, (o) 

 means an oyster eaten. (B) indicates that the indiAidual was buried. 



