192 NEW BRITISH MOSSES. 
once twisted, yet the other characters (and especially that 
derived from the calyptra) were always constant and unequi- 
vocal. 
20. Tortula marginata, B. et S. * humilis, simplex, gregaria 
vel cæspitulosa, dioica; foliis late oblongo-lanceolatis, mar- 
ginatis, costa excurrente mucronatis; capsule oblonge oper- 
culo brevirostro, peristomii membrana basilari angusta." 
Bryol. Eur. 
* T. cæspitosa (Hook. et Grev.) Montagne, Archives de bo- 
tanique, Tome I, p. 135. De Notaris Specim. de Tortul. Ital. 
No. 11. Nec Schwaegr ;” (fide B. et S.) 
Has. On walls and rocks of soft sandstone in the neighbour- 
hood of Castle-Howard, most abundant in the park quarry. 
* Stone-pits, Henfield ;? Mr. Borrer. 
When I first found this moss I hesitated to refer it to the 
Barbula marginata of the Bryol. Europ., because of its differ- 
ing in some respects from the figure and description in that 
work. Mr. Wilson, however, whom I consulted on the sub- 
ject, remarks to me, * Your Barb. marginata, if not exactly 
like the figure, etc. of Bruch and Schpr., is quite as much so 
as what I suppose to be the original in Herb. Hook. which 
has the leaves quite erect, and more linear than in Bryol. 
Eur." Through the favour of the same gentleman, I have 
lately had the opportunity of comparing it with Algerian spe- 
cimens of B. marginata, from Bové, and the differences ap- 
pear so slight that I do not scruple to consider them the same 
species. 
Tortula marginata differs from T. muralis, with which it 
frequently grows associated, in its laxer mode of growth, never 
forming dense cushions as in that species ; in the shorter stems, 
which are either simple or furnished with one short innova- 
tion; the concave, acute leaves (which in my specimens vary 
from broadly lanceolate to lineari-spathulate, but are always 
broadest where the plants are most crowded), of a paler green; 
less opaque, the margins diaphanous and thickened, and by n0 
means revolute, the nerve very slightly produced ; in the smaller 
and paler capsule; in the broader basal membrane of the 
