x Transactions of the South African Philosophical Society. 



occurs in comparatively shallow water in Iceland ; it has also 

 been found in deep waters near the Equator, and recently 

 in comparatively shallow waters in South Africa. Still more 

 instructive in this respect are the results of a recent examination 

 of the different species of Copepoda met with in South African 

 waters. It has been shown that of the species found south and 

 west of Cape Colony a considerable number occur also in the 

 northern hemisphere. Professor Cleve, who made this discovery, 

 finds in it a confirmation of his hypothesis that the waters of the 

 temperate Atlantic in the Northern Hemisphere originate not in the 

 Gulf Stream but in the Benguela current, which is supposed to 

 pass as an under-current below the waters of the tropical Atlantic. 

 I will now return to a subject I just touched upon previously, 

 viz., the occurrence of a peculiar deposit, commonly known as green 

 sand or mud, which, as recent soundings have shown, occurs 

 very extensively over the bed of the sea, off the south and west 

 coast of the Cape. A constituent has been found to be phosphate 

 Of lime which coats the coarse grain of sand inshore, and in 

 deep water where these terrigenous deposits are absent, it is 

 found encrusting and filling up the shells of Foraminifera and 

 other characteristic deep-sea deposits. It also is often found 

 as nodules formed round a central nucleus. It is therefore a 

 formation of comparatively recent date, and can hardly be 

 derived from the common mineralogical form — apatite — which 

 is found in volcanic rocks. It might be thought to be derived from 

 submarine mineral springs, but its great extent is against such a 

 supposition. Finally it might be derived from the phosphates found 

 in sea-water, but the small quantity thus found and the mode of its 

 occurrence are against this. The distinguished oceanographer, Sir 

 John Murray, has devoted particular attention to this problem, and 

 he suggested that it is derived from the phosphate of lime stored up 

 in the living organisms (specially in their bony tissue) which inhabit 

 the sea. He has observed that these deposits of green mud or sand 

 are characteristic of the regions where currents of different character 

 meet, and suggests that it is there that a great mortality amongst 

 sea animals may occur. It is of course difficult to procure direct 

 evidence on such a point, but some recent occurrences in South 

 African waters, and others of an older date, which have come to 

 light, appear to confirm this supposition in a remarkable manner. 

 I hope to give a detailed account of these on another occasion, and 

 only mention some of the main facts now. Some months ago the 

 captain of the trawler which started fishirig operations recently on 

 the Agulhas bank was startled to find one day that instead of fresh 



