240 NICHOLS: THE VEGETATION OF CONNECTICUT 
Marsupella emarginata Didymodon rubellus 
Plagiochila asplenioides Anoectangium Mougeoti 
Scapania nemorosa Plagiopus Oedert 
Radula complanata Plagiothecium denticulatum 
Lejeunea cavifolia Hylocomium brevirostre 
Hymenostylium curvirostre Thamnium alleghantense 
Inhabiting the drier cliffs, either in crevices or on the rock 
face, are such forms as: 
Metzgeria conjugata Ulota americana 
Cephaloziella Hampeana Bartramia pomiformis 
Porella platyphylloidea Hedwigia albicans 
Leucolejeunea clypeata Neckera pennata 
Frullania Asagrayana Haplohymenium triste 
Rhabdoweisia denticulata Anomodon attenuatus 
Grimmia conferta Anomodon rostratus 
The Influence of the Chemical Nature of Rocks on the Dis- 
tribution of Bryophytes—In earlier papers of this series* brief 
reference has been made to the influence of the chemical composi- 
tion of the substratum on vegetation. In glaciated regions like 
Connecticut, where most soils are transported and. residual soils 
are rare, this influence is nowhere seen to better advantage than 
in ravines and similar localities where there are exposures of bare 
rock. In Connecticut, the problem as to the effect of the chemical 
nature of the substratum on vegetation concerns chiefly calcareous 
versus potassic rocks. The granites, gneisses, schists and sand- 
stones, which comprise the bed rock over much of this state, are 
for the most part rich in potassium, which is one of the principal 
constituents of orthoclase feldspar and of mica (muscovite and 
biotite). Calcium also, as one of the components of plagioclase 
feldspar, hornblende, and certain other minerals, is present in 
some of these rocks, and in the sedimentary formations—the sand- 
stones and shales—small amounts of calcium carbonate may be 
included in the cementing material. But, except locally, the 
amount of lime in these rocks, in so far as it affects vegetation, 
appears relatively insignificant. The important lime-bearing for- 
mations of Connecticut are trap and marble. The former contains 
potassium in small amount, one or two per cent.; the latter com- 
* See Torreya 13: 109, 110. 1913; 14: 135: 1O14. 
