1903. Wright.. — Foramhiifei-al Boidde7--day, 179 



to be examined in detail under the microscope, the samples 

 being too small to be treated in an}^ other wa}-. Floatings 

 from the other clays were alone examined; in 32 of these no 

 organisms were found, this may in part be due to the first 

 floatings alone being examined, also that these minute or- 

 ganisms are at times liable to be overlooked when examining 

 the clay. To ascertain how far floatings could be relied on 

 for giving conclusive results, one ounce troy of the Boulder 

 clay from Woodburn, Carrickfergus, was examined with great 

 care. The first floating contained 1,400 specimens, the float- 

 ing process being repeated 25 times before specimens ceased 

 to come up. What remained of the cla\' was then examined 

 under the microscope, and 67 additional specimens got from 

 it. Upwards of 2,100 specimens were obtained from this 

 ounce of clay. This experiment clearly demonstrated that 

 the process of floating cannot be relied on for proving the 

 non-existence of Foraminifera in Boulder clay. 



The fauna of the Boulder clay is a peculiar one ; more than 

 half of the entire specimens found are referable to No7iio7iina 

 dep7'essula and Cassidiiliiia crassa ; the latter, wdiich is some- 

 what rare as a recent British species, is often plentiful in the 

 clay. The porcellanous forms are usually very rare, whilst the 

 Arenacea are represented only by the species Haplophrag^niuni 

 canari€7ise. It is instructive to compare the number of these 

 two sub-orders from dredgings taken in the Irish Sea, with 

 those that have been found at Inarch Hill and Rockbrook. 

 Four small specimens of Milioli7ia senmiuhmi were the only 

 Porcellana found in the Dublin clays, and there were no 

 Arenacea ; whereas, in the dredging taken off Dublin by Mr. 

 F. P. Balkwill and mj^self,'' 22 species of the former were ob- 

 tained and 19 of the latter, these being represented by thou- 

 sands of specimens. 



The marine fauna, in a climate so rigorous as must have 

 prevailed during the glacial period, could not fail to be a 

 poor one. Mr. S. A. Stewart, in his *' MoUusca of the Boulder 

 Clay of the North-Kast of Ireland " says, " Molluscan shells 

 occurring in the Boulder clay are not numerous; in most 

 cases they are only got by patient searching, and then only in 

 a fragmentary condition, but in a few instances they are less 



1 Trans. Roy. I. Acad., vol. xxviii. (Science), pp 317— 365^ 1885. 



