294 Royal Society : — 



of them arc rccf-biiiklers ; but all are essentially formed to live where 

 rapid growth and delicately cellular stnictures arc not required. The 

 forms are strong, solid, and large ; and their rapid and repeated 

 gemmation proves that theii' nutritive processes went on actively 

 and continuously. 



All the species are very much disposed to produce variations ; and 

 this is especially true as regards those which have outlived the long 

 age of the Crag, the glacial period, and the subsequent time of 

 elevations and subsidences. The least-variable species are those 

 which arc not known on other areas. 



Two of the three species which are common to the West-Indian 

 deep-sea fauna and that of our north-western coasts are also very 

 variable. 



The persistence of Madrcporaria from the earlier Cainozoic period 

 to the present time has been an established fact for several years. 

 Some of the forms which are common to the deep sea of the British 

 area and to the so-called miocene of Sicily are still existing in the 

 Mediterranean. None, however, of the species of Corals found in 

 the British Crag are represented in the deep-sea fauna. 



The existence of Mediterranean forms in the North-west British 

 area is in keeping with the discoveries of Forbes. It has, however, 

 a double significance, and bears upon the presence of West-Indian 

 forms on the North-west British marine area. There was a com- 

 munity of species between the Mediterranean and the West Indies 

 in the Cainozoic period, especially of Echinodermata, MoUusca, 

 ;Ma(h"eporaria, and Foraminifera. After the great alterations of the 

 mutual relations of land and sea which took place before the cold 

 affected the fauna of the Franco-Italian seas, this community of 

 sj)ecies diminislied ; but it lasted through all the period of Northern 

 glacialization, and is proved stiU to exist slightly by comparing the 

 Algce, the Corals, the Echinodermata, and the Mollusca. 



The presence of two very characteristic Floridan species, and one 

 less so, off the north of Scotland, is particularly interesting, because 

 they all live in the cold area and flourish there, whilst they appear 

 to be less vigorous in the warmer Gulf-stream near Florida. 



It is impossible to fail to recognize the operation of this stream 

 in producing the emigration of these three species, which are es- 

 sentially American. 



The solidity and the power of gemmation of the corals within the 

 cold area appear to be greater than elsewhere. Depth has not 

 much effect upon the nutrition of the Madr(j>oraria ; for those 

 dredged up at GOO fathoms are quite as hard and sohd as those 

 found at 300 fathoms. 



AU the calices were stuffed with small Foraminifera, and there 

 was evidently a great abundance of food. 



There were numerous Polyzoa, Sponges, Foraminifera, Diatomacea}, 

 and delicate bivalves associated with or fixed upon the corals at all 

 depths. Moreover, at from 300 to 400 fathoms, some Amjpliihelice 

 had incnistcd an Annelid. 



Serimlce, moreover, abound upon the corals ; and a pretty Isis was 



