POLYTRICHIEI. 207 



Banks of the Isla, Forfarshire, Mr. Drummond. Bearing 

 fruit on the Continent in summer. 



Forming dense green tufts, 2 or 3 inches high, brown be- 

 low. Leaf-cells below, rectangular, short, oblong, arranged in 

 lines; above, shortly hexagonal. 



The figure in the second edition of ' Muscologia Britannica/ 

 as in Grev. Sc. Crypt. Fl. t. 326, seems to be taken from 

 T. megapolitana, which differs in the cilia being appendiculate, 

 and in the leaves not so decidedly sheathing at the base. 



ORDER XVIII. POLYTRICRIEI, Brid. & Sch. 

 Sporangium often quadrangular, mostly closed by a flat 

 central tympanoid membrane, which either connects the teeth 

 or extends to the walls themselves; veil rough, with depen- 

 dent hairs, rarely naked ; leaves mostly rigid. 



61. POLYTRICHUM, Brid. 



Dioicous. Sporangium angular, with a distinct apophysis ; 

 spore-sac undulated ; peristome of sixty-four or more rarely 

 of thirty- two short teeth, composed of several fibres, and united 

 at the base by a narrow membrane; top of the columella 

 forming a circular membrane uniting the teeth ; veil densely 

 clothed with silky hairs ; nerve of leaves covered with longi- 

 tudinal plaits. 



1. Sporangium mostly 5-Q-angular ; apophysis obscure. 



1. P. sexangulare, Hoppe ; leaves rather short, spreading, 

 incurved, often secund, elongate-lanceolate, from a broad base; 

 margin thin, inflexed, mostly entire; sporangium hexagono- 

 ovate, sometimes quadrate; fruitstalk thick; veil short; lid 

 rostrate. Hook. $ Wils. t. x. ; Eng. Bot. t. 1906. 



On the tops of high mountains. Scotland. Bearing fruit 

 in autumn. 



