836 president's address. 



of many. The chief argument in its favour lies in the supposed 

 absence of deep sea deposits on dry land. 



Speaking on this subject, Professor H. Alleyne Nicholson in 

 his Presidential Address to the Royal Physical Society of Edin- 

 burgh, 1894, points out that the deepest deposits are necessarily 

 thin, scanty and of limited area. Radiolarian deposits, which are 

 supposed to indicate deep sea, have been discovered of various 

 ages. In Lanarkshire they are accompanied by green and red 

 mudstone, a forcible reminder of modern deep sea deposits. 



Professor DaA'id's observations tend to shew that radiolarian 

 deposits do not necessarily indicate deep sea. Probably in this 

 case we should have to judge by the circumstances under which the 

 Radiolaria are found, and it is to be remembered that land drifts 

 and vegetable debris may be found mixed with deep sea deposits 

 in the most incongruous manner. The dredging operations 

 between the west coast of Central America and the Galapagos 

 carried out between February and May, 1891, with the U.S. 

 Fish Commission steamer Albatross, under charge of Alexander 

 Agassiz,* showed together with characteristic globigerina ooze, 

 a large amount of decayed vegetable matter. Terrigenous 

 material was dredged up from depths of over 2,000 fathoms, and 

 with it logs, branches, twigs, and decayed vegetable matter. Off 

 the West Indies immense quantities of vegetable matter had also 

 been obtained from depths of over 1,.500 fathoms. It is e^ ident 

 that if such materials were found fossilised in such surroundings 

 the}^ would be thought to indicate shallow depths. 



Professor Poulton in his Address to the Zoological Section of 

 the British Association last year, refers to the results of some 

 of the Challenger dredgings from great depths as follows : — 

 "These most interesting facts prove furthermore that the great 

 ocean basins and continental areas have occupied the same 

 relative positions since the formation of the first stratified rocks, 

 for no oceanic deposits are found anywhere in the latter." This 



* Bulletin Museum Comparative Zoology, Harvard College, Vol. xxiii. 

 p. 12. 



