268 BOTANY OF PERTH. [November, 



tenella of British Lichenologists^ are frequent on walls, usually 

 associated with P. parietina. P. ceratophylla, var. physodes, is 

 abundant on the roots, trunks, and branches of trees, especially 

 Firs, in the woods on Kinnoull Hill, and on all the adjacent hills. 

 I have frequently met with it in fructification, both on walls and 

 trees. It presents great variety in the form and size of its la- 

 cinise, and the degree to which they are sorediiferous at their 

 extremities, and covered with minute black punctuations. The 

 latter, which are often sprinkled over the thalline laciniee, are 

 usually the spermogones of the Lichen, but are sometimes also 

 minute parasitic fringe. P. saooatilis, var. leucochroa, is also 

 common on trees as well as stones, almost everywhere through- 

 out the district, the furfuraceous form frequently predominating. 

 I have met with the latter in fine fructification on roadside trees, 

 near Pitcaithly wells. Var. omphalodes is common on the Dun- 

 keld hills ; but transition forms between var. leucochroa and om- 

 jjJialodes are sometimes found on gneissic boulders on the hill- 

 roads round Perth ; for instance, on the Strathmore Hill road, a 

 few miles beyond Bonhard. I have sometimes found it of a 

 pitchy blackness, occasionally variegated with white, from por- 

 tions of the cortical layer being eroded, exposing the subjacent 

 white, cottony, medullary layer. P. conspersa occurs on the 

 rocks of the summit of Kinnoull Hill, especially in an abortive 

 or isidioid condition. I have nowhere found this species (var. 

 latior) so abundant, or in so fine fructification, as on old walls 

 around Moftat, Dumfriesshire. P. olivacea occm's sparingly on 

 trees in the hill-woods above Kinfauns, but in good fructifica- 

 tion. Various forms of P. fahlunensis exist on the Dunkeld 

 hills, associated with other essentially alpine Lichens. P. aquila 

 is abundant on rocks on the summit of Kinnoull Hill, and in 

 good fructification. P. parietina is plentiful everywhere on trees, 

 hedges, walls, and rocks. It presents several marked varieties ; 

 one of these generally occurs on damp, shady walls, and is varie- 

 gated with white ; this is found, on careful examination, to be 

 due to partial erosion, probably by insects, of the cortical layer 

 of the thallus, exposing, as in the case of P. sawatilis, var. om- 

 phalodes, already mentioned, the white, cottony medullary tissue. 

 The apothecia are sometimes confluent or symphycarpeous, con- 

 vex and cephaloid ; they are also sometimes very numerous, but 

 very minute, occasionally they are absent. The thalline lacinise 



