294 lioijal Socielij :— 



of them arc recf-buildcrs ; but iill arc oosentiiiUy forincd to livo where 

 j-apid growtli and delicately cellular structures arc not rc(iuired. The 

 forms are stronj?, 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 cspcciidlj- true as regards those which have outlived the long 

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

 elevations and subsidences. The least-variable species arc those 

 which are not known on other areas. 



Two of the three species Avhich are common to the "West-Indian 

 deep-sea fauna and that of our nortli-Avestcrn coasts are also very 

 variable. 



The persistence of Madreporaria 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 mioceue of Sicily are still existing in the 

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

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



The existence of Mediterranean forms in the Xorth-wcst British 

 area Ls 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, 

 Madi'cporaria, 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 

 species diminished ; but it lasted throiigh all the period of Northern 

 glacialization, and is proved still to exLst slightly by comparing the 

 Alga), the Corals, the Echinodermata, and the !MoUusca. 



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 (Julf-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 cftect upon the nutrition of the Madreporaria ; for those 

 dredged up at G<>0 fathoms are quite as hard and solid as those 

 found at 3( lO fathoms. 



All the calices were stirffed with small Foraminifcra, and there 

 was evidently a great abundance of food. 



There were numerous Polyzoa, Sponges, Foraminifcra, Diatomacea?, 

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

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

 had incmsted an Annelid. 



Serpmlce, moreover, abound upon the corals ; and a pretty Tsis was 



