Ui/pnurn.] BKYACE^. 335 



convex-conical, acuminate. Peristome large ; teeth very densely- 

 articulate ; segments as long as the teeth ; cilia two or three. 

 Spores chestnut-color. — Jirachi/theciuni, Schimp. 



* Pedicel smooth. 



35. H. ISBtum, Brid. Dioecious : tufts bright or yellowish 

 green ; steins prostrate ; branches and branchlets unequal, 

 attenuate at the apex, erect : leaves close, ovate-lanceolate, 

 short-acuminate, concave, more or less plicate, narrowly costate 

 to tlie middle, minutely serrulate all around ; cells very long 

 and narrow ; perichietial leaves numerous, soft, the inner ob- 

 long, abruptly filiform-acuminate, flexuous : capsule suberect or 

 cernuous, narrowly cylindrical-oblong, slightly incurved or sub- 

 arcuate when dry ; operculum narrowly conical ; cilia strongly 

 articulate or subappendiculate ; annulus none. — Bryol. Univ. 

 ii. 479; Sulliv. Icon. Muse. 185, 1. 115. Brachythecium Imtum^ 

 Brucli & Schimp. Bryol. Eur. t. 554. 



Var. dBntatum. Leaves shorter, broader, with a shorter 

 point, more strongly dentate on the borders and more loosely 

 areolate. — H. salebrosum, Sulliv. Muse. AUegh. n. 43. B. 

 Sidlivantli, Bruch & Schimp. Bryol. Eur. BrachytJiecium, 21. 



Hab. Woods, on prostrate trunks, shaded ground, or roots of trees; 

 very frequent, and variable according as the locality is more or less damp. 



After the description of this species Schimper remarks that we have 

 in Jforth America two or three other species closely related to Brachythe- 

 cium ketuw, but which cannot be separated without careful examination. 

 On repeated comparison of a large number of specimens of this polymor- 

 phous species, in collaboration with Sullivant, wo have found a difference 

 between H. ketnm of America and that of Europe, this last agreeing with 

 the description of B. luteolum of Mueller. But so numerous are the 

 American varieties of this moss that, if only local differences were con- 

 sidered, a number of species could be established, but evidently with only 

 transient characters, like the length of the leaves, the more or less loose 

 areolation, the erect or curved capsule, etc., and even the sometimes 

 pseudo-monoecious inflorescence, differences often to be noticed upon the 

 same plant. We have therefore admitted a single species, H. Icetinn, as 

 described above, and figured in the Icones from specimens in the herba- 

 rium of Dr. Torrey labelled "i7. 20, Coll. Dewey," to which Bridel refers 

 as the materials on which he established the species. Comparing the 

 figures of the Icones with those of Bryol. Eur., the only important dif- 

 ferences to be noticed are that in the American form the capsule is gener- 

 ally larger and the upper perichietial leaves more abruptly narrowed into 

 flexuous filiform points. 



