Mr. R. Spruce on the Musei and Hepatice of the Pyrenees. 487 
: Hab. Z,_. per Pyrenzos sylvaticos, rupestris, frequens sed ra- 
rissime fructificans ; juxta lacum Séculéjo capsulis deoperculatis, 
22 Sept. 1845, legi. 
307. Z. viridissimus, Smith, Fl. Brit. p. 1224 (sub Dicrano) ; 
Br. Europ. /.c. p. 7. t. 1; M. P. 243. 
Hab. Z, ad arbores circa Pau et Bagnéres, plerumque sterilis. 
308. Z. conoideus, Schwgr. Suppl. 2. p. 138. t. 187; Br. Europ. 
f¢. pd. t. 2. 
Hab. Z, P. c. in truncis populi vetustis juxta pagum Pouwzac ! 
(Philippe l). Estafforte, Hte. Garonne (Brondeau in hb. Dufour). 
In these specimens the leaves are often nerved throughout, and 
the nerve even excurrent into ashortmucro. The sporular sac rises 
above the mouth of the capsule before it is divided into cilia, which 
are two cellules in breadth near the base, sometimes sixteen in number, 
the intercalary cilia being far shorter than the others. 
Tribus 25. PrycHoMITRIEA. 
60. Ptychomitrium, Bryol. Europ. 
309. P. polyphyllum, Dicks. Crypt. fase. 3. p. 7 (sub Bryo) ; 
Br. Europ. Ptychom. p. 4. t. 1; M. P. 244. 
Hab. Z,_3 in saxis graniticis ‘regionum sylvaticarum : e vulga- 
tissimis. 
310. P. incurvum, Muehl. Cat. Plant. Amer. Sept. p. 98 (sub 
Grimmia). Weisia incurva, Schwgr. Suppl. 2. p. 51. t. 116. 
Grimmia Muehlenbergii, Brid. Br. Univ. 1. p. 181. Ptychomi- 
trium pusillum, B. et S.! Br. Europ. Ptychom. p. 5. t. 1; Sulli- 
vant ! Musci Allegh. n. 135. 
Hab. Z, P. occ. in muro prope Oloron. Czespitem unicum in- 
venl. 
Leaves composed of two layers of cellules except near the base ; 
the margins often thickened (=2 cellules) ; the nerve= 3-5 cellules ; 
the obtuse apex cucullate. é 
Tribus 26. OrruorricHaces, Bryol. Kurop. (ex parte). 
61. Orthotrichum, Hedwig. 
Obs. This genus includes but few rupestral species, and only two 
of these (O. anomalum and cupulatum) have their normal station on 
calcareous rock. Of. the species which inhabit the bark of trees, it 
is remarkable that those with an ezserted capsule (UJota, Bridel) pre- 
fer young oaks, while those with an immersed capsule prefer poplars, 
§ 1. (= Utorta, Bridel.) 
311. O. crispulum, Bruch. Mst. in Bnd. Br. Univ. 1. p. 793 ; 
Br. Europ.! Orthotrichum, p. 23. t. 12; M. P. 245. 
Hab. Zyjn¢, ad arbores in sylvis Pyren. occidentalium, locis 
Jurangon, Gan, &e. 
