MARINE BIOLOGICAL STATION AT PORT ERIN. 29 



derived from the shells and other 

 hard parts of the animals and plants 

 living on the bottom. 

 3. Planktonic (Murray's pelagic) — where the greater 



part of the deposit is formed of the 

 remains of free-swimming animals 

 and plants which lived in the sea 

 above the deposit. 

 The last group is Murray's ''pelagic" unchanged, and 

 that, there can be no doubt, is a natural group of deposits; 

 but Murray's "terrigenous" is an unnatural or hetero- 

 geneous assemblage containing some deposits, such as the 

 gravel off Bradda Head and the sand of the Liverpool bar, 

 which are clearly terrigenous in their origin, along with 

 others such as shelly sands and nullipore deposits which 

 have much less to do with the waste of the land, but 

 are very largely organic in origin and formed by animals 

 and plants in situ. The proposal is then to recognise this 

 latter group of deposits by separating them from the 

 truly terrigenous under the name " Neritic." Probably 

 some of the Coral sands described by Murray and Renard 

 in their Challenger Report on Sea-Deposits would also 

 fall into this category. 



Professor Johannes Walther, of Jena, who has of recent 

 years been working on the borderlands of geology and 

 bionomics, in a recent letter to me on my proposed 

 classification of deposits says : — " Ich meine dass der 

 Ausdruck benthonisch statt neritisch richtiger ware. Denn 

 es kommt doch bei der Diagnose weniger daraufan, 

 dass die Ablagerung in der Flachsee, als dass sie durch 

 benthonisch Organismen (Coralline, Korallen, Echinoder- 

 men, Mollusken, Bryozoen, etc.) gebildet wird." With 

 this I can quite agree. I lay most stress on the nature 

 (bottom plants and animals) of the particles composing 



