1 88 ROSS: PTILIDIUM PULCHERRIMUM (WEB), HAMPE. 
ground to about 6 feet up the trunk. Also growing on the tree 
are some lichens, two mosses, Dicranum scoparium and one of the 
Hypnacece, and the hepatic Lophocolea heterophylla. Lichens, 
mosses, and L. heterophylla appear amongst the Ptilidium , 
even when at first sight this seems to be growing in dense patches. 
In places, the lichens are in possession. The Dicranum is in 
tufts, as well as scattered ; and, at the foot of the tree, the 
Lophocolea has established itself. The tree is evidently a favour¬ 
able situation, and there is some competition for sites on its bark. 
From the area of the trunk on which the Ptilidium is found 
and from the amount of old plant some of the clumps show, one 
concludes that it has been there some time. A somewhat 
remarkable feature is the ease with which patches of the 
Ptilidium can be lifted from the tree trunk, especially where 
it grows most densely. Last summer, a long branch of a held 
rose reached the tree ; and, in high winds, this may have been 
forced across the trunk and may have scratched off hepatic, 
moss, and lichen. Pieces of Ptilidium were found on the ground, 
but these may have been washed off by heavy rains. The 
branch of the held rose is no longer there to do damage ; but, after 
the recent thaw, six or seven pieces of hepatic and moss, chiefly 
Ptilidium , were found on the ground near the base of the tree, 
and three pieces of Ptilidium were hanging precariously, clearly 
the work of the melting or slipping snow. At hrst, one con¬ 
cluded from the depth of the patches that new plants of Ptilidium 
had grown upon old ones, or that the older parts of 
the plants had died and the hold on the tree trunk 
had loosened. This may be so in some instances, but 
the examination of a patch of plants in the course of 
preparation for preservation revealed that the Ptilidium 
had overgrown the Hypnum. It would also seem able 
to spread its way into a tuft of plants of Dicranum. Lichen 
seems apt, on the other hand, to establish colonies amongst the 
Ptilidium. As already stated, Lophocolea heterophylla holds 
sway at the foot of the tree ; and, in preparing Ptilidium for 
the collection, one was rather surprised to find, amongst a patch 
of Ptilidium plants, young and healthy plants of L. heterophylla. 
These plants were frequently growing underneath, rather than 
at the top level of, the Ptilidium, and now and then forced their 
way through and showed on the surface of the Ptilidium growth. 
