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 A HISTORY OF SURREY are the following : Thomasiana and mucronatum at Chobham and Thursley Commons, Americana and radiosa at the Mill Pond east of Chapel Wood, and Jenneri and angulosa at Thursley Common. The rarer species of Xanthidium that occur are : concinnum var. Boldtianum at Thursley Common, and Smithii var. -variabile at Devil's Jumps, Frensham. The large genus Cosmarium is represented by no less than ninety-eight species ; the follow- ing are a few of the rarer ones : Ralfsii on Chobham Common, pachyder- mum at Mitcham Common and at Mill Pond east of Chapel Wood, subtumidum at Devil's Jumps, Frensham, isthmium, Gregorii, fontigenum and succisum on Puttenham Common, inconspicuum on Mitcham Common, Quasillus at Esher West-end and Wimbledon Commons, quinarium, pygmceum and Broomei at Mill Pond east of Chapel Wood, Blyttii and Regnellii at Bisley Common, truncatellum on Chobham Common, subcren- atum at Witley Common, eboracense at Richmond Park, Nymannianum, cristatum, ortbostichum, margaritatum (most abundant), amasnum, cymatonoto- pborum, sphagnicolum, pseudoprotuberans, elegantissimum, nitidulum and vario- latum at Thursley Common. The large genus Staurastrum is also well represented, the following being some of the rarer ones : glabrum on Bisley Common, O'Mearii on Thursley and Puttenham Commons, incon- spicuum and sibiricum at Devil's Jumps, Frensham, turgescens at Wimbledon Common, sexcostatum at Esher West-end Common, oxyacanthum, pseudo- sebaldi, asperum, corniculatum, pachyrbynchum, subpygmceum, lanceolatum and brevispinum at Thursley Common, iotanum, micron and tunguscanum at Puttenham Common. Tetragonium lacustre is only known from Esher Common ; Ccelastrumverrucosum also occurs at Esher Common. Pedias- trum glanduliferum is very fine at Bisley. Scenedesmus antennatus is abundant on Puttenham Common and Rbaphidium convolutum occurs in Richmond Park. TetraSdron tetragonum occurs in Ditton Marsh and Dimorpbococcus lunatus with Dasyglasa amorpba and Gloiotrichia pisum are found on Thursley Common. Scytonema figuratum is found on Esher West-end Common. Cbroococcus pallidus, Glceothece confluent and G. linearis occur on Thursley Common. The student who may continue the investigation of the algae of the county will find plenty of work to do, some districts not having been visited at all and others only at certain times of the year. LICHENS (Licbenes] Lichens flourish only where there is a moist atmosphere and full exposure to sun and pure air. They are therefore very rarely seen in the neighbourhood of smoky cities, almost the only species known to exist in the Surrey suburbs of London being Lecanora galactina, which, with the sub-species dissipata, occur in the Crystal Palace grounds ; and Urceolaria scruposa, which has been found in Kew Gardens. But as a rule until a distance of ten or fifteen miles from London is reached, it is only a waste of time to search for well developed lichens, the thallus in a more or less undeveloped state being alone met with. Lichens are there- 60