98 Rey. T. Salwey : Lest of the scarce Lichens found 
Collema velutinum, Ach. Upon ash-trees at Craig-y-Rhu. Dr. Tay- 
lor refers this to nigrum. 
Solorina saccata. Wickliff Rocks, Ludlow : scarce. 
Peltidea venosa. Ditto. Ditto. - 
P. scutatc. On trees at Pentregaer, in fruit. 
P. horizontalis. Wickliff Rocks, Ludlow, Craigforda, &c. 
P. aphthosa. Craigforda, and woods at Downton Castle, Here- 
fordshire. 
P. spuria. Dry banks at Oswestry, but very scarce. Ido not 
regard this as the same with venosa. If not a distinct species, I 
should consider it with Fries a state of canina. Though about the 
same size as venosa, the spuria is distinguished from it by not having 
the thick dark-coloured veins underneath which that plant has, and 
by the apothecia being smaller and narrower. In venosa they are of 
a roundish shape and flat, something like those of horizontalis, but 
of a dark colour like those of scutata. ‘There is a Peltidea I have 
occasionally met with, which I believe is regarded, if it has been no- 
ticed at all, as the young state of canina; it is however of much less 
frequent occurrence than the canina, whilst the great difference in 
habit and appearance inclines me to believe it to be a distinct one. 
It is of an extremely thin and delicate texture, of a light bluish co- 
lour, and grows in an imbricated manner, forming cushion-shaped 
plants upon dry bare banks. The segments of the thallus are cir- 
cular and inflexed, and the surface is copiously sprinkled by white 
soft sorediz. It has much the habit and appearance of Sticta lim- 
bata. Though I would not undertake to affirm that it is not the 
young state of canina, I am inclined to think it is not. 1 am satis- 
fied that a most patient and long-continued examination of parti- 
cular plants in the same locality is required to enable us to clear up 
many difficulties which make the study of the Lichens so perplexing. 
P. polydactyla. This is not so common as either rufescens or ca- 
nina. I never saw it growing in such perfection as upon some 
heaps of burnt turf upon a common which had been left for two or 
three years before they were spread. I mention this because lichens 
are generally considered to be, and certainly are usually, of very slow 
growth, and yet here, where the turf on which they were growing 
had undergone the action of fire, the plants were of a larger size 
than usual, grew in the greatest profusion, and were copiously 
fringed with apothecia. Now even admitting that the original ve- 
getation upon these heaps had not been destroyed by the fire, but 
that the plants in question escaped, still their unusual growth and 
luxuriance were unquestionably influenced by the alteration the soil 
had undergone. It has been suppposed however that lichens de- 
rive their nourishment only through the media of air and light: 
«Typicus lichenum omnium proventus est in aére et luce,” says 
Fries. I cannot but think however that in the instance now men- 
tioned, the rapid growth and luxuriance of the plants must have 
arisen from their deriving some nourishment through their roots, if 
the fibres attaching the thallus to the soil may be so considered. I 
have seen frequently an analogous case in the Hepatice, the old beds 
