696 Proceedings of the Royal Irish Academy. 



at the Antipodes. It has never yet heen got in Scotland, though 

 I have zealously searched for it ever since its first discovery. I 

 was, however, successful in finding it in the west of Ireland in 

 August, 1892. It occurred in a peat-bog near Westport, where 

 the turf-cutters had left a series of trenches, about 4-^ feet wide 

 from 30 to 100 feet long, and about 3 feet deep, all filled with 

 water as brown as port wine. This peat-bog, with its series of 

 trenches, proved to be a happy hunting-ground, for each trench 

 had its own peculiar feature. In one of them Pedalion was in 

 abundance, associated with many other interesting forms ; and 

 strange to say not a single example of it was to be found in any 

 of the other trenches, although there was but a few yards of 

 separation between. Another of the trenches contained a luxu- 

 riant growth of Sphagnum, and on each leaf, CEcistes pilula was 

 set as thickly as it could stand ; while in another trench there 

 was a growth of Chara and Utricularia, on which Melicerta 

 conifera were very prolific, and associated with it were numerous 

 examples of four species of Floscularia. The water of each 

 trench without exception contained SyncJiceta pectinata and S. 

 tremula. In some obscure way, the conditions in each ditch 

 favoured the development of the Synchaeta while repelling one 

 or more of the other species. I transferred gallons of water 

 from the trench containing the Pedalion to the other trenches, 

 but failed completely to establish it in any of them, although 

 there was no perceptible difference between them or the water 

 they respectively contained. I visited this peat-bog every day 

 for three weeks in August, 1892, and sent many consignments of 

 the Pedalion to my correspondents in England and Scotland. 

 When I made my last visit in 1894, I found the bog altered; 

 the trenches were filled up and all my fine Pedalion gone. 

 However, I had no great reason to complain, for I found a 

 species, if not as conspicuous, yet nearly quite as rare, namely, 

 Triphylus lacustris, which was growing very plentifully in a 

 small pool on the old spot. The only species remaining in the 

 pools of this bog, to represent what were found in 1892, was the 

 Melicerta conifera. The haunts and habits of Potifers are strange. 

 Some species may be found to inhabit the same pool year after 

 year at the same season; on the other hand some species will 

 inhabit the water of a pool or lake at one time in abundance, 

 then disappearing not to be found in the same habitat for many 

 years, until again they reappear in thousands. 



