PLcelLfol. 14. MUSCI. 363. Didymodon. 743 
5. Didymodon rigidulum. Stiffish twin-tooth . 
Leaves closely tiledlike on all sides, lanceolate, very 
pointed, keeled; main rib stiff, running beyond the point; 
capsules oblong, ovate, upright ; lid beaked. 
Didymodon rigidulum, Hedw. S. Muse. 104. 
Bryum rigidulum, Dickson Crypt. 4, 12. 
Trichostomum rigidulum. Turner M. Hib. 34 ; Engl. Bot. 2173. 
Bryum lineare, Dickson Crypt. 3, 6. 
Trichostomum lineare, Engl. Bot. 1598. 
On rocks and walls; perennial; April. 
Very similar to tortula fallax, gen. 355, sp. 8. 
6. Didymodon trifarium. Three-rowed twin-tooth . 
Leaves rather distant, somewhat three-rowed, lanceolate, 
bluntish, keeled ; main rib scarcely reaching the^tip ; cap- 
sule oblong, ovate, upright; lid beaked. 
Didymodon trifarium, Swartz M. Suec. 28. 
Cynontodium trifarium, Hedw. S. Muse. 57. 
Swartzia trifaria, Hedw. Crypt. 2, 76. 
Bryum trifarium, Dickson Crypt. 3,8. 
Trichostomum trifarium, Engl. Bot. 1707. 
Trichostomum linoides, Engl. Bot. 2295, not of Dickson. 
On moist banks. 
7. Didymodon capillaceum . Hairy twin-tooth . 
Stem long ; leaves nearly 2-rowed, awlshape, bristlelike ; 
capsule upright, ovate, cylindrical; lid conical. 
Trichostomum capillaceum, Engl. Bot. 1152. 
Cynontodium capillaceum, Hedw. S. Muse. 57. 
Swartzia capillacea, Hedw. Crypt. 2, 72. 
Didymodon capillaceum, Schrad. Germ. 64. 
Bryum capillaceum, Dickson Crypt . 1, 4. 
Bryum sestivum, Hudson An gl. 485. 
On mountain banks. 
8. Didymodon heteromallum. Odd-sided twin-tooth . 
Stem rather short ; leaves mostly facing one way, awl- 
shape ; capsule ovate, cylindrical ; lid conical. 
Grimmia heteromalla, Roth Germ. 3, 145 ; Engl. Bot. 1899. 
Weissia heteromalla, Hedw. S. Muse. 71. 
Afzelia heteromalla, Ehrh. Crypt. 173. 
Bryum Weissia, Dickson Crypt. 2,5. 
Didymodon heteromallum, Hedw . S. Muse. 23. 
On mountains. 
