23. Genus DESMATODON, Bridel. 
Whole Plant — Perennial, in tufts, varying in height from J to I inch. 
Stem — Somewhat branched, from lline to i inch in height. 
Leaves — Spreading, oval-oblong, very similar to those of A. Starheana, with strong norve, thickened near the apex, excur- 
rent, concave ; areolas small and round in the upper part, rectangular at the base. 
iNrLOEESCENCE — Monoicous. 
Barren Floiver (Antheridta) — Gemmiform. 
Fertile Floioer (Archegonfa). 
Vaginula — Oblong. 
Capsule — Oval, reddish-brown, on a straight pedicel, erect. 
Calyptra. — Cucullate, long. 
Operculum — Conical, having a longish beak. 
Annulus — None. 
Peristome — Single, with 16 teeth, connected in pairs, erect, red, varying in length. 
Spores — Small. 
General Habitat — On clayey banks by the sea coast. Pruit: — March. 
Species Illustrated — Desmatodon nervosus (Br. & Sch.), Trichostomum convolutum (Brid.-). 
Reference to Plate — a, Plant, natural size ; aa, Same, X 2-in. ; b, Stem leaves, X 1-in. ; d, Basal cells, X i-in. ; e, Calyptra, 
X 1-in.; /, Capsule, X 1-in.; ./J, Teeth of peristome, X i-in. ; g, Operculum, X 1-in.; h, Spores, X 
i-in. ; i, Vaginula, X 1-in. 
This genus is represented in Britain by two species according to Wilson. Hobkirk remarks, vide " Tortula." 
24. Genus DISTICHIUM, Br. & Sch. 
Whole Plant — Perennial, oeespitose, with innovations, and dichotomously branched, from 1 inch to 2 inches in height. 
Stem — Plexuose, erect, with radicles. 
Leaves — Distichous, glossy, flexnose, spreading, dilated, subulate, with a broad conspicuous nerve ; areolae small on the 
upper part. 
Inflorescence — Monoicous. 
Barren Flower (Antheridta) — Naked, axillary, cylindrical. 
Fertile Flower (Archegonia) — Having long styles, paraphyses short. 
Vaginula — Oblong. 
Capsule — Oblong, erect, or subcylindrical, on a long slender fruit stalk, colour reddish, or olive brown. 
Calyptra — Cucullate, with slender beak. 
Operculum — Conical. 
Peristome — Teeth 16, single, linear, bifarious. 
Annulus — Broad and distinct. 
Spores — Smooth, small. 
General Habitat — Alpine situations, on the mountains of Wales, Ireland, and North Britain. Fruit: - Summer. 
Species Illustrated — Distichium capillaceum (Br. & Sch.), Didymodon capillaceus (Web. & Mohr., Hook. & Tayl.). 
Reference to Plate — a, Plant, natural size ; aa, Same, X 2-in. ; 6, Stem leaf, X 2-in. ; hh, Same, X 1-in. ; c, Apices of stem 
leaf, X i-in. ; d. Cells of mid-leaf, X i-in. ; /, Portion of capsule, X 1-in.; ff, Teeth of peristome, X 
i-in. ; g, Branch, X 1-in. 
This genus is represented in Britain by two species. 
25. Genus DIDYMODON, Br. & Sch. 
Whole Plant — Perennial, erect, from J to 1 inch in height, slightly caespitose, growing usually on the ground. 
Stem — Branched, with innovations at the base, reaching to an equal height. 
Leaves — Lanceolate, with acuminate points; margins, recurved, entire, having dot-like cellules above, opaque; basal cells 
large, elongated, semi-transparent ; lower leaves reddish, by which it is easily distinguished. 
Inflorescence — As in Tortula and TricJwstomum. 
Barren Flower (Antheridia) — Gemmiform, with oblong anthers. 
Fertile Flower (Archegonia). 
Vaginula — Oblong. 
Capsule — Erect, on a long fruit stalk. 
Calyptra — Cucullate, reaching more than half way down the capsule. 
Operculum — Conical, with a short beak. 
Peristome — With 16 lanceolate teeth, variable in size and structure, colour pale reddish. 
Annulus — Narrow and simple. ^ 
Spores — Small. 
General Habitat — On a clayey or a gravelly soil, limestone walls, and shady rocks. Fruit : — Spring and winter. 
Species Illustrated — Didymodon rubellus (Br. & Sch.), Weissia curvirostra (Hook. & Tayl.). 
Reference to Plate — a, Plant, natural size; aa, Same, X 2-in.; h, Stem leaves, X 1-in.; /, Capsule, X 1-in.; ffTeeth. of 
peristome, X i-in. ; g, Operculum, X 1-in. 
This genus is represented in Britain by six species according to Hobkirk. Wilson observes that it is closely allied to 
Trichostomum, and is also connected with Anacalypta and Desmatodon. 
8 
