254 ORTHOTRICHACE^E. 



Var. /8. rivale Wils. Leaves of a succulent texture, broad, 

 obtuse, or shortly apiculate, not imbricated when dry. Calyptra 

 narrow ; capsule more exserted, broader, and less tapering below, 

 less contracted when dry, ribs broader, of 4-5 rows of cells. 



Var. 7. fastigiatum Hiibn. (O '. fastigiatum Bruch., plur. auct. ; 

 O. neglectum Scrip., Syn.). Shorter and more compact in all its 

 parts, dark green ; leaves shorter, less papillose, areolation 

 larger, hexagonal, thin-walled ; capsule more immersed, shorter, 

 more contracted and -urceolate when dry, the ribs broader, 

 processes of inner peristome wider. 



Hab. Trees, sometimes on stones, very common. The var $. on trees by 

 streams, not common ; the var. y. rare. Fr. summer. 



This is our commonest species, and very variable. The capsule especially varies 

 in the amount of its exsertion and in form. The var. rivale should perhaps be merged 

 in the var. fastigiatum. The latter is another of those forms which have been 

 described as separate species on constantly changing and inadequate grounds, and it is 

 very doubtful whether all the characters above given are ever to be found together on 

 any plants ; on the whole however the lax, thin-walled areolation and shorter, more 

 urceolate capsule, are the most characteristic features. 



D. TENELLA. 



9. Orthotriehum rivulare Turn. (Tab. XXXV. G.). 



In dark green or blackish loose tufts, often floating and 

 elongated, 1-2 inches long. Leaves spreading, when dry loosely 

 incumbent, broadly oblong-Ungulate , somewhat variable in form 

 above, broad and rounded or somewhat abruptly narrowed, but 

 always obtuse in general outline, with or without a short blunt 

 apiculus ; sometimes cucullate ; entire or irregularly denticulate 

 or eroded at apex ; margin recurved throughout ; nerve prominent 

 at back, ceasing some way below the summit ; cells rather large, 

 about 10 jj. in diameter, rounded or rounded-quadrate, incrassate, 

 faintly papillose; at base quadrate-rectangular, not much 

 enlarged. Capsule immersed or more or less exserted, oval or 

 oval-oblong, abruptly contracted into the seta, when dry and 

 empty strongly contracted below the mouth, dark brown ; ribs 8, 

 strong, wide, shining; calyptra inflated, smooth, dull green, 

 without hairs ; peristome double, outer teeth united in 8 pairs, 

 when dry reflexed against the wall of the capsule, finely papillose ; 

 processes 16, incurved, long ; the alternate ones often ill- 

 developed. Vaginula slightly hairy. Stomata immersed, almost 



