ISOTHECII. 149 



cylindrical sporangium, and shorter, more densely leafy stems, 

 which has been found in Sussex by Mr. Mitten. 



25. THAMNIUM, Schimp. 



Sporangium symmetrical or slightly uusymmetrical, hori- 

 zontal or cernuous ; peristome double, the inner with or 

 without intermediate cilia; primary stem (rhizoma) creep- 

 ing, secondary erect, dendroid ; leaf-cells above rounded, those 

 of the base more elongated. — Distinguished from Hypnum 

 by its very peculiar habit, in which it agrees with Climacium. 

 There are many exotic species, some of which could not be 

 placed in Isothecium, with which the only British species has 

 been associated more from convenience than conviction. 



1. T. alopecurum, Br. 8$ Sch. ; secondary stem nearly 

 naked below, pinnate above with frequently pinnate some- 

 what complanate branches ; leaves spreading, ovato-lanceolate, 

 sharply toothed; nerve reaching nearly to the apex; spo- 

 rangium ovate, more or less inclined ; lid rostrate. — Hook. §• 

 Wils. t. xxv.; Eng. Bot. 1. 1182. ; (Plate 13, fig. 1) ; Moug. % 

 Nest. n. 144. 



In moist shady woods and on rocks. Common. Bearing 

 fruit in winter and spring. 



Dioicous. Rhizoma throwing out many radicles ; secondary 

 stem 2 or 3 inches high, clothed below with minute, scattered, 

 scale-like, pale, ovate, acuminate leaves, distichously pinnate 

 above as are the branches, which are often curved; leaves 

 more or less complanate, opaque, ovate or ovato-lanceolate, 

 pointed, but scarcely acuminate, sharply toothed; nerve strong, 

 vanishing below the apex ; cells in the upper part of the leaf 

 short, rounded, or subquadrate, more elongated at the base, 

 and at the slightly reflected angles ; fruitstalk scarcely an inch 

 long, reddish, even ; sporangia more or less aggregate, ovate, 



