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 imiversally distributed species. Amongst these may be 

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

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

 Cfimhriata, Linn., infrequent, and its vars. tub(sfor))iis,'Flk., radiata, Schreb., 

 as at Enfield and Pinner; C.fiircata, HofFm., and its var. racemoaa, HoiFm., 

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

 AVeald; Cladina sylvatica, Linn., and C. rangifcrina, Hoffm., on heaths and 

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

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

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

 ingly and barren ; Eainalina calicaris, Ach., and its vars. fastigiaia, Pers., 

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

 condition ; Pcltigcra canina, on mossy banks, and on the ground in woods, 

 not uncommon ; P. fohjdadyla, Hoffm., in mo-'st places of shady woods, 

 rare, as at Hampstead and Pinner ; Parmclia raperata. Dill., rare, on trees 

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

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

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

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

 stcUaris, var. Idspida, Dill., on the ground on heaths, but by no means well 

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

 infrequent ; P. farktina, Linn., on roofs of hoiises, pretty common, and its 

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

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

 scarcely fertile ; Lecanora suhfusca, Linn., on trees and walls in the suburbs 

 and country, common, and its var. atrynca, 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 ; Psora 

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

 Fhichley, and abundant near Totteridge, but never fertile ; Lecidea cancs- 

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

 grata, Frs., on old pales near water, rare, as on the Finchley Koad; L. 

 sahidetorum. Elk., 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. uUginosa, 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 ; Opegrapha 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 ; Graphis scripta, Linn., on the 

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

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

 indla, Nyl., on wood (pales) near London, rare ; Stigmatidium crasstun, on 

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

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

 not very uncommon, as at Ealing and near Totteridge ; C. trichicde, Ach., ou 

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

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



