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Dr. P. Martin Duncan on the 



[Mar. 24 ; 



appear to be greater than elsewhere. Depth has not much effect upon 

 the nutrition of the Madreporaria ; for those dredged up at 600 fathoms 

 are quite as hard and solid as those found at 300 fathoms. 



All the calices were stuffed with small Foraminifera, and there was evi- 

 dently a great abundance of food. 



There were numerous Polyzoa, Sponges, Foraminifera, Diatomaceoe, and 

 delicate bivalves associated with or fixed upon the corals at all depths. 

 Moreover, at from 300 to 400 fathoms, some Amphihelice had iucrusted 

 an Annelid. 



Serpula, moreover, abound upon the corals ; and a pretty Iris was asso- 

 ciated with them at a depth of 705 fathoms. This is a fauna which, if 

 covered up and presented to the palaeontologist, would be, and would have 

 been for some years past, considered a deep-sea one. 



It is a fauna which indicates the existence of the same processes of nu- 

 trition and of destructive assimilation and reproduction which are recognized 

 in association with corresponding forms at less depths and in higher tem- 

 peratures. 



The great lesson which it reads is, that vital processes can go on in cer- 

 tain animals at prodigious depths, and in much cold, quite as well as in less 

 depths and in considerable heat. It suggests that a great number of the 

 Invertebrata are not much affected by temperature, and that the supply of 

 food is the most important matter in their economy. 



The researches of Hooker, who obtained Polyzoa and Foraminifera 

 in soundings at a depth of nearly 400 fathoms off the icy barrier of the 

 South Pacific, of Wallich in the xltlantic, and of Alphonse Milne-Edwards iu 

 the Mediterranean have had much influence upon geological thought in 

 this age, which, so far as geologists are concerned, is remarkably averse to 

 theory. For many years before any very deep soundings had been taken 

 with the view of searching the sea-bottom for life, geologists had more or 

 less definite opinions concerning the deposition of organisms in sediments 

 at great depths. Certainly more than thirty years ago deep-sea deposits 

 were separated by geologists from those which they considered to have 

 been formed in shallower seas. The finely divided sediment of strata con- 

 taining Crinoids, Brachiopods, Foraminifera, and simple Madreporaria was 

 supposed to have been deposited in deeper water than formations containing 

 large pebbles, stones, and the mollusca whose representatives now live in 

 shallows. The relations of such strata to each other during subsidence, 

 the first being found occasionally to overlap the last, proved that there 

 was a deeper sea-fauna in the offing of the old shores which were 

 tenanted by littoral and shallow-water species. The deposition of strata 

 containing Foraminifera, Madreporaria, and Echinodermata, whose lime- 

 stone is remarkably free from any foreign substances, has been consi- 

 dered to have taken place in very deep water ; this theory has been 

 founded upon the observations of the naturalist and mineralogist. Indeed 

 no geologist has hesitated in assigning a great depth to the origin of some 



