NOTES OX THE ALG.i: OF LEICESTERSHIRE 265 



approach to a " mountainous tract," consists of Trias marls and lime- 

 stones with an outcrop of pre- Cambrian rocks. The algal flora of 

 the Charnwood Hills affords evidence of the abundance of Desmids 

 said to be characteristic of such tracts — /'. e. mountains consisting of 

 pre-Cambrian rocks (Gr. S. West, British Freshwater AlycB, p. 6). 

 The genera Arthrodesmus, Fuastrum, and Micrasterias are found 

 exclusively in this district ; Pleurotceniiun here and in the immediate 

 vicinity ; Closterium mainly here. West .says " In mountainous 

 ax'eas the filamentous forms are chiefly representatives of the Myxo- 

 jjhycecd and Conjiiijatce.'''' Mougeotia is certainly commoner here 

 than in other parts of the count}^ ; the Myxophycece are present 

 though not markedly prevalent. It may here be noted that the 

 genus Vaucheria is scarcely found in this region, though abundant in 

 other parts of the county. 



Geologically Leicestershire may be roughly divided into three 

 parts — the Charnwood District, the district west of the R. Soar con- 

 sisting of lied Marl (Trias), and the district east of the Soar 

 consisting of Lias clays and limestones. Of these the Charnwood 

 district is the richest in Algae, and the Lias clays are the poorest. 



Collections have been made at all seasons of the 3'^ear, though 

 most frequently in spring and summer. The two months in which 

 the winter conditions of low temjjerature and prolonged darkness are 

 most pronounced are, of course, December and January. The genera 

 which have been observed in the samples gathered in these months 

 and which may therefore be looked upon as the hardiest are : — 

 CEdogonium, Ulothrix, Microspora, Vaucheria, Mougeotia, Zyynema, 

 S^yirogyra, Cosmarium, Closterium, Conferva, and Oscillatoria, 

 together with certain Flagellates {Trachelomonas volvocina, species 

 of Euglena) and cold-loving diatoms (e.g. Meridian circuJare Ag., 

 Hantzschia amphioxys (Ehr. ) Grun.). On the other hand, some of 

 the genera not yet found in December and January, though noticed 

 in most of the other months of the year, are Cladophora, Fediastrum, 

 and Anaboena. The decrease in amount of Cladophora fracta in 

 winter has been noticed in other places (see '" Biology and Ecology of 

 the Algal Flora of Abbot's Pool, near Bristol" (Fritsch and Rich) in 

 Proc. Bristol Nat. Soc. 4th Seiies, ii. pt. 2 (1909)). Samples have 

 been obtained from large and small ponds, reservoirs, streams, rivers 

 and canals, from the outflow of the furnace boilers at Coalville, and 

 the hot water of the cooling reservoir at the Belgrave Sewage 

 Pumpiiig-station. Cladophora shows a marked preference for the 

 well aerated waters, for out of 23 localities in the county in which 

 it has been found, one was a swiftly-flowing stream in Grace Dieu 

 Woods, one was a weir at Baggrave Hall, one was a rapid stream at 

 Kirby Muxloe, five were ordinary little streams (Little Dalby, 

 Thurnbv, Ingarsbj^ Barkby, Quorn), six were rivers or canals, two 

 were ditches, four were large pieces of water, and only three were 

 small ponds ((ilenfield, Medbourne, and Laughton). 



The Zygneviacew are very well represented in Leicestershire, and a 

 few special observations have been made on them. Species of Mou- 

 geotia are of common occurrence and are often present in considerable 

 amount, though West in the Handbook for Birmingham, edited by 



