172 DUBLIN UNIVERSITY 



the information that it was new to Britain ; and as he has also kindly 

 undertaken to lay before the Association a scientific description, I will 

 not attempt any minutiae on that subject. 



But questions regarding the economy of Platyarthrus, the observer 

 alone can determine, and accordingly the following inquiries have been 

 made of me : — 



First Query. The species of the ant in whose nests it was found ? 



Unfortunately, I did not think of retaining specimens, which might 

 have enabled me to speak with positive certainty. The nests were 

 those of red, yellow, and black ants — the latter a much smaller species 

 than either of the others, the workers of which were about equal in size. 

 As far as memory would determine, they were severally Formica rufa, 

 F. flava, and F. nigra of Smith. P. Hoffmanseggii was most numerous 

 among the red ants, and in smallest numbers among the yellow. 



Second Query. Are the Oniscoids found in the nest, or adhering to 

 the stone ? 



In most instances they are seen in the chambers of the nest, when 

 the overlying stone is removed ; and the rapidity with which they dive 

 into the subterranean galleries and disappear from sight shows that they 

 are familiar with the internal portion of the formicarium. Sometimes 

 it is impossible to find them again, even by digging. On two or three 

 occasions, however, I found them on the under side of the stone, appa- 

 rently in a state of repose (as some of them are in the nest itself also, 

 when first exposed to light) ; and once a single individual occurred to me 

 on the under side of a stone not covering a formicarium ; yet even in 

 this case there was a nest close by, and several ants running about 

 beneath the stone. 



Third Query. Do the ants ever carry off the Oniscoid, as they do 

 Aphides ? 



This I have not seen done ; but it is quite possible they may do it 

 sometimes, for my observations were not sufficiently extended to prove 

 the point either one way or the other. 



Fourth Query. The number of Oniscoids usually found in each nest? 



The largest number I have seen in a single nest is eight or nine, and 

 that was in the first found, in which also were some of the finest speci- 

 mens I saw. In some formicaria there are only two or three Oniscoids, 

 so that the average probably lies between these numbers. But they are 

 •not by any means to be had in every nest in the locality — in fact, the 



