PLATE VII 



i. Emarginida fissura, Linn. 



2. Bellerophon bicarinatus, Lev. Fossil : Carboniferous. 



3. Scissurella crispata y Flem. 



4. Pleurotoma Babylonia, Linn. 



5. Pleurotomaria Anglica, Sby. Fossil : Lias. 



6. Trochotoma conuloides, Dell. Fossil : Jurassic. 



7. Rirnula exquisita, A. Ad. 



8. Haliotis tuberculata, Linn. 



9. Architectonica ferspectivum, Linn., showing the open umbilicus. 



10. Architectonica perspectivum , Linn., lateral view. 



11. Sections of shell of Comes ponderosus, Hwass (diagrammatic) : 



A, longitudinal section ~\ a, outer layer; b, middle layer; c, 



B, transverse section j inner layer; d, e, f, lines of growth. 



12. Transverse section of Conns tesselatus, Hwass, to show absorption 

 of the inner walls to make room for the growing animal. 



13. Section of a Cone, whose apex had been perforated by boring 

 bivalves, Lithodomus, showing the deposition of shelly septa to 

 protect the occupant from the intruders. 



14. Cacum imperforatum, G. Ad. (marine) : a, young shell ; b, adul/ 

 showing the destruction of the apex as growth proceeds. 



15. Rumina decollata, Linn, (terrestrial) : a, young shell ; b, adult 

 shell, showing a similar condition. 



%* Fig. 9, original drawing by Miss G. M. Woodward. All the others 

 by S. P. Woodward. 



