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 



