TRANSACTIONS OF THE SECTIONS. 



85 



Genera. 



Radiolites 



(Solenoconchia.) 

 Dentalium 



Gastropoda. 



Actaeon 



Aporrhais 



Avellana 



Calyptrcea 



Cerithium 



Columbellina 



Dimorphosoma . . . 



Dolium 



Emarginula 



Fusus 



Gibbula 



Hipponyx 



Natica 



Patella 



Pleurotomaria 



Pterocera 



Rostellaria 



Scalaria 



Solarium 



Trochus 



Turbo 



Turritella 



Cephalopoda 



Ammonites 



Ancyloceras 



Aptychus 



Baculites 



Belemnitella 



Belemnites 



Crioceras 



Hamites 



Helicoceras 



Nautilus 



Scapbites 



Turrilites 



Anisoceras 



No. of species in 

 Chalk-marl. 



1 

 2 

 1 



i 



2 

 •2 



i 

 i 



3 



i 



i 



i 



i 



18 



29 

 1 



'i 



1 

 3 



10 

 1 



11 

 1 



58 



No. of species in 

 Lower Chalk. 



1 

 3 



1 



1 



'2 



1 

 3 



1 

 .3 

 1 



22 



31 



2 

 9 



10 



2 



11 



63 



No. of species in 

 Upper Chalk. 



2 



i 



i 

 3 



1 

 1 

 2 



13 



6 

 1 

 3 



t • 



1 



1 

 1 

 2 



25 



A glance at the above list, and, much more, an inspection of the Chalk Mollusca 

 in a good collection, ought to convince any conchologist that all these genera were 

 comparatively shallow- water forms. I should infer that the depth might have been 

 from low-water mark to 40 or 50 fathoms. None of the genera are deep-water. 

 Charna, Ostrea, Pitma, Calyptrcca, Hippomjx, and, most assuredly, Patella cannot 



