1908-1909.] j3 9 



Dickson, Mr. C. M. Cunningham, and Mr. W. J. Fennell 



expressed their views on the line of argument used by the 

 lecturer. 



"THE LIFE-HISTORY OF THE WATER-BEETLE." 



The third meeting of the session was held in the Museum, 

 College Square North, on 19th January— the President (Mr. R. 

 Patterson, F.L.S., M.R.I. A.) in the chair. 



Mr. Frank Balfour-Browne, M.A. (Oxon), F.R.S.E., F.Z.S., 

 delivered a lecture " On the Life-history of the Water-beetle." 

 He pointed out that water-beetles had not been very extensively 

 studied, as they were, so far as was at present known, of no direct 

 economic importance. The tendency nowadays was to devote 

 attention to useful and harmful organisms, so that practically all 

 the work on water-beetles dated back a great many years, and was 

 due to the labours of such old-time naturalists as Lyonnet, 

 Schiodte, Miger, Reaumur, De Geer, and others. Most of the 

 work done on the group appeared to have been concentrated 

 upon a few of the larger species, Dytiscus and Hydrophilns having 

 been the favourite studies, but even in these genera there seemed 

 to be plenty still to be learnt if one would but pay careful 

 attention to them. Mr. Balfour-Browne based his lecture upon 

 the two types mentioned, with a view to showing that, even 

 although he had only spent a short time on these, the statements 

 of the older observers were not always to be taken as final. He 

 also described the life-history of a common species, Hydrobius 

 /usages, which he had studied in detail during the past season. 

 Dealing first with Dytiscus, he described the secondary differences 

 between the sexes, and mentioned the egg-laying habits of the 

 female, which pierced holes with her ovipositor in submerged 

 water plants, laying a single egg in each hole. The time taken 

 by the egg to hatch, although usually given as about three weeks, 

 varied considerably with the time of year in which they were laid, 



