TORTULACE^.J 193 [Pottia. 



or with a peristome of i5 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 oi 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 infl. 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. 



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. iii, 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 (i8ig) ; Bry. univ. i, 25 (1826). 

 ScHWAEG. Suppl. I, P. I, II (1811). La Pyl. 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. 11, 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 (i860). Jaeg. Bar. der St. Gall. nat. ges. i86g, p 82. 

 HoBK Syn. br. m. 28 (1873). Husn. Mouss. nord-ouest. 35 (1873). Juratz. Laubm. 

 oester.-ung. 91 (1882). 



