22 The Irish Naturalist. February, 



made use of to ])rove physical changes, if such have occurred. 

 The excavations for the floating dock and basin^ recently 

 constructed by the Harbour Commissioners at what was 

 known as " Thompson's Bank " and the " Point Fields " 

 afforded a capital chance to investigate the deposit of 

 estuarine clay that has been slowly forming in our bay, 

 and of collecting a complete series of its fossils. This clay 

 attains at Thompson's Bank a thickness of over twenty feet. 

 It reaches away up to the Plains, and as far as the first 

 lock of the Lagan Canal, and stretches westwards to the 

 Bog Meadows. It is found under our streets in the low- 

 lying districts, as may be noticed when sewers are being 

 excavated. This clay is also seen at Sydenham, inter- 

 stratified with the sands of that shore, and at the Kinnegar 

 at Holywood it occurs below the gravel which is so charged 

 with flint -flakes. A bed of blue clay at Bally holme, I 

 believe, also belongs to the estuarine clay period, and 

 likewise a small patch at Kilroot, which, as at Holywood, 

 underlies flint gravel. The shells in all these various places 

 round the lough are identical with the species collected at 

 the docks, but a bed that I discovered at Magheramorne 

 on Lame Lough yields not only abundance of shells, but 

 also a number of species not found here. I have visited 

 this bed three times, but there arc no excavations, and one 

 is restricted to such things as he can pick out at the surface 

 or two or three feet below it. We cannot therefore say 

 that our knowledge of it is complete. But merely picking 

 and scraping as it were at the surface has produced forty- 

 eight species of shells. The profuse abundance of fora- 

 minifera is remarkable ; on my last visit Mr. Swanston, 

 who accompanied me, brought away some of the clay to 

 examine for these small forms, and we have not met with 

 them so abundant anywhere else in the locality. The dock 

 excavations at Belfast have been carried to a depth of 

 some twenty feet below high water mark. I have availed 

 myself of the opportunity thus afforded, and am able to 

 present you with an account of the fauna of the deposit, 

 and of the inferences that one is compelled to draw from 

 the character of that fauna, and the mode of its distribution. 

 At the lowest portion of the clay reached by digging we 



'Spencer Basin. 



