TORTULACE^E.] 1Q3 [Pottid. 



or with a peristome of 16 teeth, rudimentary or imperfect, or flat lanceo- 

 late and united at base by a narrow membrane, bipartite, of a double 

 lamina, solid and papillose. Spores granulose. Inhabiting the ground 

 and crevices of rocks. Der. after Prof. Pott of Brunswick. 



This genus is by Mitten and Lindberg regarded as a section of Tortula, 

 and the foliage will be seen to approach very closely that of Desmatodon, e.g., 

 Tort, muralis. 



It is perhaps better to keep it separate as it possesses a certain natural 

 habit, and a considerable number of species nearly 40 which have many 

 points in common, and when a peristome is present, it does not run out into 

 cilia as in Tortula ; the male inn 1 , must be observed early in the season, as it 

 is often caducous before the maturity of the fruit. I attach considerable 

 importance to the smoothness or scabrosity of the calyptra, as it affords a 

 valuable character to discriminate species, otherwise very closely allied. 



CLAVIS TO THE SPECIES. 

 Lid minute, persistent. 



Capsule globose. recta. 



Capsule elliptic, acuminate bryoides. 



Lid distinct, deciduous. 

 Leaves quinquefarious. 

 Nerve not excurrent. 



Leaves divergent serrulate towards apex. Heimii. 



Leaves imbricated, entire. latifolia. 



Nerve excurrent. 



Calyptra smooth. 



Leaves with upper cells smooth. 



Capsule turbinate. trwicatula. 



Capsule oval-cylindric. littoralis. 



Leaves with upper cells papillose. 



Upper cells larger, peristome none. intermedia. 



Upper cells smaller, peristome present. 



Nerve excurrent in a long point. lanceolata. 



Nerve forming a short mucro. ccespitosa. 



Calyptra scabrous. 



Lid conic obtuse. Starkei. 



Lid rostrate. asperula. 



Leaves octofarious. 



Calyptra smooth. 



Nerve excurrent in a short point. viridifolia. 



Nerve excurrent in a long point. crinita. 



Calyptra scabrous. Wilsoni. 



i. POTTIA RECTA (With.) Mitt. 



Paroicous ; leaves broader, oblongo-lanceolate, papillose at back. 

 Capsule subglobose, exserted on an erect pedicel ; lid distinct, persistent ; 

 cal. rough at point. (T. XXVIII, B.). 



SYN. Phascum curvicollum SM. Eng. Bot. t. 330 (1796). 



Phascum rectum WITH. Bot. arr. Br. veg. 3 ed. Hi, 787, t. 18, f. i (1796). HULL Br. Fl. P 

 2, 252 (1799). SM. Eng. Bot. sub t. 905 (1801) ; Fl. brit. 1153 (1804). TURN. Muse. 

 hib. 4 (1804). BRID. Sp. muse. I, 2 (1806) ; Mant. 6 (1819) ; Bry. univ. i. 25 (1826). 

 SCHWAEG. Suppl. I, P. I, ii (1811). LAPYL. Journ. Bot. 1813, p. 279. HOOK. TAYL. 

 Muse. br. 9, t. 5 (1818). GRAY Nat. arr. br. pi. i, 712 (1821). HOOK. Br. fl. ii, 4 (1833). 

 HUEBEN. Muse. germ. 12 (1833). BR. SCHIMP. Bry. eur. fasc. I, p. ii, t. 5 (1837) et 

 fasc. 43, t. 2. DE NOT. Syll. 302 (1838) ; Epil. bri. ital. 734 (1869). RABENH. Deutsch. 

 kr. fl. ii, S. 3, 83 (1848). C. MUELL. Synops. i, 27 (1849). WILS. Bry. br. 31, t. 5 

 (1855). SCHIMP. Synops. 20 (1860). JAEG. Ber. der St. Gall. nat. ges. 1869, p 82 

 HOBK Syn. br. m. 28 (1873). HUSN. Mouss. nord-ouest. 35 (1873). JURATS. Laubm.' 

 oester.-ung. 91 (1882). 



