98 MESSRS. J. А. WHELDON AND W. G. TRAVIS ON 
DC., are partial to bare limestone, but require some degree of dampness 
and shade. 
Some of these calciphile species occur also on mortar of walls, and in 
this way obtain a wider distribution. The following have been met with 
only on mortar ог the like, namely, Lecanora urbana, Nyl., L. umbrina, Nyl., 
Lecidea atrofusca, Mudd, Verrucaria muralis, Ach., V. integra, Carroll, 
Thelidium microcarpum, А. L. Sm., T. incavatum, Mudd, and Staurothele 
hymenogonia, A. Zahlbr. 
In contradistinction to the foregoing species, which are true lithophytes, 
we may distinguish another group of lichens which require an earthy sub- 
stratum with some amount of humus. The following have been met with in 
our area growing on the ground about limestone rocks, or in their crevices 
among earthy detritus and incrusting decaying mosses and other plants :— 
Collema yranuliferum, Nyl., C. pulposum, Ach., C. melenum, Ach., Colle- 
modium turgidum, Nyl., Peltigera rufescens, Hoffm., Lecidea lurida, Ach., 
Biatorina cwruleo-nigricans, А. L. Bm., Bilimbia lignaria, Massal., Bacidia 
muscorum, Mudd, and Dermatocarpon lachneum, А. L. Xm. (Endocarpon 
rufescens, Ach.). Оп horizontal limestone rock-surfaces small depressions 
are frequently formed by solution, and in these a black earth collects. This 
is a favourite habitat for Lecidea lurida, Ach., Biatorina cæruleo-nigricans, 
А. L. Sm., and Dermatocarpon lachneum, A. L. Sm. The crevices and joints 
of limestone walls, particularly in somewhat damp, shady situations, and 
where not too overgrown by moss, yield the following :—Collema furvum, 
Ach., C. pulposum, Ach., C. cheileum, Ach., Lecanora dispersa, Nyl., Cladonia 
cæspititia, Floerke, Gyalecta cupularis, Schaer., Bilimbia aromatica, Jatta, 
B. sabuletorum, Branth & Rostr., B. lignaria, Massal., and Bacidia muscorum, 
Mudd. 
Another group of calcareous rocks in the same district is afforded by the 
strata known as the Pendleside Series, exposed on the northern slopes of 
Pendle Hill, and comprising a series of impure limestones and mudstones. 
Many of the lichens referred to in connection with the Carboniferous Lime- 
stone occur also on these rocks. They also yield Rhizocarpon confervoides, 
DC., Lecidea ochracea, Wedd., Biatorina chalybeia, Mudd, and Lilimbia sub- 
viridescens, А. L. Sm., which have not yet been found with us on the 
Carboniferous Limestone. 
On the banks of the В. Ribble at Chatburn are high banks of glacial elay 
containing pebbles of limestone and sandstone. This locality has yielded a 
number of interesting lichens, more especially Lecidea expansa, Nyl., Verru- 
caria submersa, Schaer., Thelidium mesotropum, A. L. Sm., and Microglæna 
nuda, nov. spec., which оссиг on the exposed surface of small stones partially 
embedded in the clay. Many of the limestone pebbles, when extracted from 
the clayey matrix, are found to be pitted on all their faces by the action of 
former generations of lichens which lived on them and were destroyed when 
