344 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



and Pelagic), so as adequately to represent the conditions 

 obtaining in shallow waters like the Irish Sea. The classifica- 

 tion proposed is as follows : — 



1. Terrigenous (Murray's term restricted) — where the 

 deposit is formed chiefly (say, at least two-thirds, 

 66 %) of mineral particles derived from the waste of 

 the land. 



2. Neritic — where the deposit is largely of organic. origin, 

 its calcareous matter being 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. 



It is evident that some such classification as the above 

 was very necessary. Murray's term " terrigenous " was 

 coined to represent those deposits which were formed from 

 the wastage and weathering of adjoining land-surfaces. In 

 the Irish Sea, however, where, from their position, the deposits 

 ought all to be terrigenous, many are found to contain as little 

 as 17 % of Silica, and are formed of the remains of bottom- 

 living animals. Such deposits as these, examples of which are 

 the Nullipore and Shelly bottoms, so common in certain areas, 

 could not possibly, it is evident, be classified under the term 

 "terrigenous" and, therefore, the new division was found 

 necessary, and has been adopted. 



In the Proceedings of the Liverpool Geological Society for 

 the year 1897-98, a most interesting and comprehensive paper 

 is contributed by Herdman and Lomas, on the " Floor Deposits 

 of the Irish Sea." In this paper it is shown how the deposits 

 covering the bottom of the Irish Sea have been the result of 

 (1) the denudation of the coasts, (2) the redistribution of 

 the older deposits under the sea, and (3) vital agencies — the 



