HYPNUM. 469 



[One of the most natural of the sub-divisions of Hypnum ; 

 H . incurvatum alone, perhaps, of our British mosses, presenting 

 some considerable divergence from the general type ; in the form 

 and direction of the leaves, however, it is quite analogous to H . 

 cupressiforme var. resupinatum. With these two exceptions all 

 the species are at once known by the more or less falcato-secund, 

 two-nerved or nerveless, longly acuminate leaves, all curved 

 downwards, usually in two rows one on each side of the stem or 

 branch, so that the upper side or back of the stem is smooth, 

 often glossy, while the lower side or front is irregular and rough 

 with the leaf-points. H . cupressiforme may be looked upon as 

 the type of this Section, and the student will do well to study it 

 in its various forms as a help to the understanding of the allied 

 species, which it is usually convenient to describe by comparison 

 with the plant in question.] 



/Stem rigid; branches pectinate ; Is. deeply plicate 26. crista- castrensis 



\Ls. not, or only slightly plicate when moist 2 



/Ls. with broad, cordate, auriculate base 3 



\Ls. ovate-lanceolate, not cordate at base 4 



/Ls. serrulate, usually crisped and twisted at points when dry 25. mollusciim 



•'(.Ls. entire or sinuolate only, scarcely crisped 23. procerrimum 



/Ls. not at all auricled 20. hamulosum 



^\Ls. more or less distinctly auricled 5 



/Angular cells swollen, hyaline 6 



->\Angular cells more or less thickened or coloured 7 



,/Ls. with widish acumen ; stem sparingly branched 18. Patientits 



\ Ls. with very fine acumen ; stem pinnate 21. caliichroum 



/Ls. secund, pointing upwards, narrow ; branches incurved ij. incurvatum 



' \Ls. usually falcato-secund, generally wider at base 8 



o / Leaf-margin narrowly revolute almost to apex ig. revolutum 



\ Margin plane, or slightly recurved only 9 



{Leaves circinate ; cells incrassate ; stem scarcely pinnate 22. Bambergeri 

 Leaves more or less falcate ; cells thinner ; stem usually pinnate 10 



{Ls. rather wide at base, red-brown at junction with the brown stem.. ly. imponens 

 Ls. narrower at base, not coloured at junction with the paler stem II 



/Capsule oblong-cylindric ; ls. rarely strongly denticulate 16. cupressiforme 



1 : \ Capsule shortly oval ; ls. sharply denticulate 24. canariense 



15. Hypnum incurvatum Schrad. (Stereodon incurvatus 

 Mitt.) (Tab. LVIII. C). 



Very slender, green or yellowish green, in small silky tufts. 

 Stems prostrate, irregularly branched or sub-pinnate, branches 

 short, usually curved. Leaves rather close, homomallous and 

 usually pointing upwards, almost straight or more or less curved 

 and falcato-secund, less spreading when dry, very small, \ line 

 long, oblong-lanceolate, gradually and longly acuminate, at 

 margin plane, entire or faintly denticulate at apex, nerve double, 



