DIDYMODON. 65 



the teeth approximate very closely in pairs, in D. caplllaceum 

 and keteromallum less so : moreover in the latter each tooth has 

 frequently a longitudinal cleft down its centre. 



* Capsules inclined. 



1. D. purpureum ; stems scarcely branched ; leaves lanceolate, 



acuminate, carinate, their margins recurved, entire ; cap- 

 sule ovato-cylindraceous, oblique, substrumose, furrowed 

 when dry ; lid conical. (TAB. XX.) 



Dicranum purpureum. Hedw. Sp. Muse. t. 36. Turn. Muse. Hib. 

 p. 72. Engl. Bot. t. 2262. Mong. et Nestl. n. 24. Mnium purpureum. 

 L'mn. Bryum bipartitum. Dicks. Engl. Bot. t. 2357. Dicranum 

 strictum. Engl. Bot. t. 2294. Bryum strictum. Dicks. Dicranum 

 Celsii. Engl. Bot. t. 2418. Bryum Celsii. L'mn. Trichostomnm 

 papillosum. Engl. Bot. t. 2533. Bryum tenue. Dicks. D. interme- 

 dium. Hedw. Sp. Muse. t. 31. f. 1-6. 



HAB. On the ground and on moist banks. 



This plant is abundant in Europe, not being uncommon 

 in the warm parts, though seeming to prefer the colder re- 

 gions. In Iceland it covers the ground in large patches, as 

 well as in Greenland, whence Professor Giesecke has, among 

 other cryptogarnous plants, brought beautiful specimens of 

 this. The synonyms enumerated above can scarcely be 

 doubted to belong to this species. It varies extremely in 

 the length of the stems, but is very constant in the shape of 

 the leaves, of the capsule furnished with a struma, sulcated 

 when dry, and of its conical lid. The teeth of the peri- 

 stome are so long, so narrow, and deeply divided, as to de- 

 mand a removal of this plant to the genus Didi/modon^ and 

 indeed Sir James Smith has, from the observations of Mr. 

 Turner, actually described a variety of it in that section of 

 his genus Trlchoslomum which corresponds to the Didy~ 

 tnodon of Hedwig, under the name of T. papillosum. 



2. D. indmalum ; leaves bifarious, from a sheathing base, subu- 



late; capsule ovate, inclined ; lid conical. (TAB. XX.) 



Didymodon inclinatum. Swartz Muse. Suec. Bryum inclination. 

 Dicks. Swartzia inclinata. Hedw. St. Cr. v. 2. t. 2/. Cynontodium 

 inclinatum. Hedw. Sry. Muse. p. 58, Grimmia inclinata, Engl. Bot. 

 t. 1824. 



HAB. On mountain rocks, rare. 



The teeth of the peristome are so broad as to be remark- 

 able in this genus, and to render it doubtful whether it 

 should be arranged as Sir James Smith has done, under his 



