BOTANY SCALE-MOSSES, LIVERWORTS AND CRYSTALWORTS The list of Essex Hepaticas includes only the commonest species, with the exception of Trichocolea tomentella and Ptilidium ci/iare, which are characteristic of subalpine boggy woods and moorlands, and where they occur there must almost certainly be other unrecorded species. The genera Kanft'a, Cephalozia, Lejeunia, yungermannia, Reboulia and Zegatella are almost certain to occur in the county. The list must therefore be considered an imperfect one. Frullania dilatata, Dumort Plagiochila asplenioides, Dumort Radula complanata, Dumort Aplozia crenulata, Dumort Porella platyphylla, Carr & Pears inflata, Huds. Ptilidium ciliare, Nees Nardia scalaris, Carr Trichocolea tomentella, Ehrh. Pellia epiphylla, Corda Lepidozia reptans, Dumort Metzgeria furcata, Dumort Scapania undulata, Dumort Aneura multifida, Dumort nemorosa, Dumort Marchantia polymorpha, Necs Diplophyllum albicans, Dumort Lunularia vulgaris, Mich. Lophocolea bidentata, Dumort Riccia glauca, Linn. heterophylla, Dumort Ricciella fluitans, Braun. LICHENS (Lichenes] The Epping Forest district of Essex and the neighbourhood of Kelvedon are the only portions of the county from which the lichen flora has been at all fully recorded. It is therefore difficult to estimate what wealth of lichens the county possesses, for there are other districts, such as Hatfield Forest and some well wooded portions of the county, worth investigating. Lichens occur more particularly upon trees and upon rocks. The majority of lichens are of extremely slow development, remaining latent except when the moisture and other conditions of the atmosphere are favourable. It is therefore upon comparatively old trees and in situations suitable to their requirements that one would expect to find interesting species. Owing to the former bad management of the Epping Forest, the Rev. J. M. Crombie tells us in 1883 that its lichen flora was not so good as it would be under better conditions, and that the species had diminished in numbers since the time when he first visited it, but I am informed that under the new management of the forest the lichen flora is improving. Granitic sandstone and calcareous rocks which some lichens love so well do not occur in the county ; it is therefore only upon the stonework and upon the brickwork of old buildings that these species are represented. The first records of lichens are in Turner and Dillwyn's Botanist's Guide, published in 1805, where fifteen species are enumerated. The next list was by Mr. Edward Forster, to whom the county owes so much. More recently the Rev. James M. Crombie has brought our knowledge up to date. 1 1 On the Lichen Flora of Epping Forest and the causes of its recent diminution,' Transactlmu Eiiex Field Club, iv. 54, 1886. 53
