HYPNUM. 479 



oval or oblong, straight or slightly curved, dark purplish brown, 

 horizontal, hardly constricted below the mouth when empty. 

 Lid sharply pointed. Calyptra slightly hairy when young. 

 Dioicous. 



Var. p. condensatum Schp. More robust, less regularly 

 pinnate, with stout, somewhat fasti giate branches; bright golden 

 green, often with a rusty tinge ; stem and branch-leaves larger, 

 closely and regularly falcato-secund, strongly hooked at the tips 

 of the branches, distinctly plicate when dry. 



Var. y. fastigiatum Bosw. (Hobkirk, Syn., Ed. II.). 

 Slender, branches erect, less closely pinnate, somewhat jastigiate ; 

 leaves less crowded, small, less strongly falcate. 



Hab. Calcareous soil and mountain rocks by streams. Common. The var. /3 

 on mountain rocks by streams, less common ; the var. 7, Derbyshire. Fruit summer. 



H. molluscum although somewhat variable has a facies of its own which is 

 generally easily recognised ; the soft dense tufts, more closely and regularly pinnate, 

 with the leaves very densely imbricated, Bexuose and undulated at points, principally 

 contribute to this. Under the microscope the strongly denticulate, broadly cordate 

 stem-leaves with the angular cells somewhat enlarged but otherwise hardly different 

 from the rest of the areolation, readily separate it from its allies. For its relationship 

 to Hyocomitim flagellare, see the description of that plant. 



Schimper separates this species under the sub-genus Ctenidium, retained as a 

 genus by Lindberg, partly on account of the shortly ovate inflated capsule of solid 

 texture ; but although this is often a marked feature, it also frequently happens that 

 the capsule is longer, longly if widely oblong, and sometimes arcuate, while the 

 texture is sometimes, at least, less solid ; in short in no way differing from some forms 

 of H. ctipressiforme and other allied species. 



The end walls of the cells not unfrequently project in minute points at the back 

 of the leaf, forming scattered, acute, very small papilla?. 



The var. fastigiatum is a very marked, slender form, of a dull, olive green in the 

 specimens I have seen ; it does not appear to be the same form as the var. erectum 

 of Schimper, which is tall, pinnate and with the branch-leaves less finely acuminate. 

 Our variety, found in Derbyshire, was originally referred to H. canariense Mitt. 



The var. condensatum is a marked variety, and H. croceum Tayl. MS., from 

 Killarney is probably referable here. 



H. molluscum usually differs from H. procerrinium, in addition to other points 

 mentioned under that plant, in the less marked disproportion of the stem-leaves to 

 those of the branches ; in the more robust forms the stem-leaves in H. molluscum are 

 as large as in that species, but the branch-leaves then appear always to increase in 

 equal proportion. This is especially the case in the var. condensatum, where they are 

 large, very regularly falcate, glossy, and distinctly plicate when dry. 



26. Hypnum crista-castrensis L. (Ptilium crista-castrensis 

 Lindb.) (Tab. LIX. A.). 



Tall, very robust ; stems erect, or ascending, simple or twice 

 or thrice divided, 3-5 inches long, very regularly and beautifully 

 pinnate with dense, complanate branches, giving a strikingly 

 regular plumose appearance to the plant ; in large loose tufts or 

 masses of a bright yellowish green, pale below. Branches almost 



