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VIl. Hydrogonium C. Mueller. 

 40.D.Ehrenbergii Lorentz. — Trichoetomum Lor.; Didymodon 

 Kindb.; Trichostomum (Hydrogonium) mediterraneum CM. 



Leaves sublinear or ovate-lanceolate subobtuse not (or indi- 

 stinctly near base) reflexed, patent when moist; basal cells 

 narrow hyaline, the others smooth subpellucid sparingly chloro- 

 phyllose; costa not or scarcely excurrent. Capsules unknown. 

 Stem often 3 — 6 c. m. high. — . Wet calcareous rocks r. Eur. 

 » France: Taxis »: Boulay (Africa, Alger: Debat; Philibert). 

 116. Pottia Ehrhart. 



A. Leaves smooth with hyaline cells. Paroecious. 

 l.P.veiiUSta Juratzka. 



» Upper leaves long obovate-oblong spathulate short-acuminate 

 not reflexed; costa excurrent. Capsule oval-cylindric; teeth 

 none; annulus double persistent. — Eur.»: Schimper {»Asia 

 island Cyprus: Unger»: Jur.). 

 2.F.pallida Lindberg. 



» Leaves recurved near middle, shorter than in the last. 

 Capsule oval-oblong; annulus none. Smaller than the last. — 

 Eur. r. Spain: J. Lange»: Schimper. 



B. Leaves often papillose; cells more or less chlorophyllose. 

 a. Paroecious. Leaves us. reflexed and papillose; costa 



long-excurrent. 

 3.P.crinita Wilson. 



Leaves broadly oblong-lingulate obtusate often obtuse, papil- 

 lose and reflexed. Capsule us. suboval; teeth wanting or rudi- 

 mentary; pedicel orange; calyptra us. smooth — Moist banks 

 and rocks near sea r. Eu^. Engl.: Ralfs. 



* P.vii'idifolia Mitten; Braithwaite. 



Lower leaf-cells shorter, the upper smaller. Peristome none. 

 — Rocks near sea r. Eur. Irel.: Stewart. France: Le Jolis. 



* P.asperula Mitten; Braithwaite. 



Leaf-cells as in P. crinita *viridifoUa. Peristome none. Ca- 

 lyptra scabrous. — Eur. r. Engl.: Curnow. 



* P.Wilsoni Hooker. — Gymnostomum Hook.; Pottia Br. eur. 



Lower leaf-cells long narrow, the upper very small. Capsule 

 narrower; teeth rudimentary. Calyptra scabrous. — Sandy 

 rocky ground r. Eur. France: Lamy. Engl.: Curnow. Amer. 

 »U. S.»: Lesq. et Jam. 

 4.P.ciineifolia Solms Laubach. 



Lower leaves linear-oblong, the upper longer and spathulate- 

 oblong subobtuse smooth r. refl^exed. Capsule oval-oblong 



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