406 APPENDIX. 



suburbs do we find any great improvement, though one or two very common 

 species here begin to appear on the coping of walls about villas. It is only 

 when we reach the higher grounds in the county to the north and west, at 

 some distance from London, that we find, in suitable habitats, several of the 

 more frequent and universally distributed species. Amongst these may be 

 mentioned the following, though doubtless some others may on further ex- 

 amination be detected : — Cladonia liyxidata, Linn., not uncommon on heaths ; 

 C.fimbriata, Linn., infrequent, audits vars. tub(gformis,'Flk., radiata, Schreb., 

 as at Enfield and Pinner; C.furcata, Hoffm., and its var. racemosa, Hoffm., 

 not very uncommon in woods ; C. coccifcra, Ach., common, as on Harrow 

 Weald; Cladma sylvatica, Linn., and C. rangiferina, Hoffm., on heaths and 

 in woods, but barren ; BcBomyces rufus, De C., rare on heaths, and scarcely 

 fertile ; Us7iea barhata, Frs. var. hirta, Linn., on old trees in woods, barren, 

 and not well developed ; Evernia jorimastri, Ach., on trees in woods, spar- 

 ingly and barren; Eamalina ccdicaris, Ach., and its vars. fastiglata, Pers., 

 farinacea, Linn., not uncommon on trees and hedges, but seldom in good 

 condition ; PelUgera cmiina, on mossy banks, and on the ground in woods, 

 not uncommon ; P. polydactyla, Hoffiu., in moist places of shady woods, 

 rare, as at Hampstead and Pinner ; Parmelia caperata, Dill., rare, on trees 

 and old pales in the higher tracts, and always barren ; P. saxafilis, Linn., on 

 the trunks of old trees in woods, not frequent nor fertile ; P. olivaceo., on 

 trunks and branches of trees, rare, as at Pinner ; P. loerlata, Linn., on the 

 trunks of aged trees, here and there in the north of the county ; Physcia 

 stellaris, var. hispida, Dill., on the ground on heaths, but by no means well 

 developed ; Physcia ccesia, on old walls and roofs of houses, probably not 

 infrequent ; P. parietina, Linn., on roofs of houses, pretty common, and its 

 forms viridis, Schreb., and citrinella, Frs., on old pales, even in the suburbs 

 of London ; Placodium onurorum, on old brick walls and grave-stones, but 

 scarcely fertile ; Lecanora subfusca, Linn., on trees and walls in the subiu'bs 

 and country, common, and its var. atrynea, Ach., frequent on old pales ; L. 

 exigua, on aged trees and old roofs, probably not rare ; L. atra, Huds., on 

 brick walls, at least in the northern districts ; L. varia, Ehrh., common on 

 old trees and pales, as also its var, symmicta, Ach., but rarely fertile ; Vsora 

 ostrcata, Hoffm., on old pales, not unfrequent in the northern tracts, as at 

 Einchley, and abundant near Totteridge, but never fertile ; Lecidea cmies- 

 cens, Dcks., common on the trunks of old trees, but always barren ; L. deni- 

 grata,'Frs., on old pales near water, rare, as on the Einchley Eoad; L. 

 sabuletorum, Flk., on decaying mosses on shaded brick walls, probably not 

 rare ; 8. pelidna, Ach., on calcareous and arenaceous stones, as bridges and 

 churchyards, not unfrequent in the rural districts; L. uliginosa, Ach., on 

 clayey soil on heaths frequent, and abundant at Hampstead ; L. parasema, 

 Ach., on the trunks of trees and on pales, frequent in the north and west of 

 the county ; L. myriocarpa, De C, on old posts and pales on the borders of 

 fields, apparently not uncommon ; Opegrapiha varia, Pers., on the bark of 

 various trees, pretty frequent ; 0. atra, Pers., on the smooth bark of young 

 trees, not rare on the outskirts of woods ; Grapkis script a, Linn., on the 

 trunks of trees in woods, common and variable; Arthonia astroidea, Ach., 

 on the smooth bark of trees, apparently rare, as at Pinner ; A. mclasper- 

 mdla, Nyl., on wood (pales) near London, rare; Stigmatidium crassum, on 

 the bark of old hornbeams, perhaps not unfrequent in the north of the 

 county ; Ccdicium curium, Turn. & Borr., on old pales and decaying trees, 

 not very uncommon, as at Ealing and near Totteridge ; C. trichiale, Ach., on 

 old posts, probably not rare, as about Hendon ; Pertusaria communis, D. C, 

 on the trunks of large trees, chiefly beech, in shady woods, common ; P. 



