394 HYPNACEyE. 



1. Isothecium myurum Brid. {Hypnum myurum Poll. ; 

 Isothecium viviparum Lindb.) (Tab. LI I. B.). 



In large bright or yellowish green, rather rigid, glossy- 

 patches. Secondary stems erect or drooping, with numerous 

 somewhat crowded branches pointing in one direction, curved, 

 usually terete when dry, with the leaves imbricated, or longer, 

 attenuated and sub-flagelliform, with laxer leaves. Leaves 

 concave, widely ovate-oblong, acute or shortly or widely apiculate, 

 rarely shortly piliform-acuminate ; those of the branches smaller, 

 less acuminate ; margin plane or very slightly recurved at base, 

 above involute, at apex slightly denticulate ; nerve thin and 

 narrow, rarely stout, sometimes slightly forked above, reaching 

 to the middle of the leaf or slightly higher ; cells of the greater 

 part of the leaf narrow-linear, obtuse, vermicular, incrassate, 

 about 6-10 times as long as broad ; towards mid-base more 

 elongated, above shorter, at apex wide and shortly rhomboid ; at 

 basal angles wide, rounded-quadrate or shortly oblong, 1-2 times 

 as long as broad, often yellowish, opaque, forming minute 

 auricles ; a few rows at margin above these short, sub-quadrate. 

 Perichstial bracts sheathing, acuminate, erect, with the points 

 only slightly divergent. Seta smooth ; capsule orange-brown, 

 erect, elliptic-oblong or oblong, with a short neck ; lid rostrate, 

 straight or slightly curved ; peristome small. 



Var. f3. minus Bagnall {Notes on the Flora of Warwickshire, 

 p. 40). Very slender, leaves very small, acute ; areolation lax, 

 with the walls hardly incrassate. 



Hab. Trunks of trees ; more rarely on rocks or earth. Common. The var. 3 

 in several localities in Warwickshire (Bagnall). Fr. spring. 



This species, although dioicous, is frequently found fruiting, and is therefore easily 

 known from all its allies except Eurhynchium myosuroides. The latter plant bears a 

 great resemblance to it, but is clearly distinct in its spreading, almost squarrose, 

 perichsetial leaves and its more elongated angular cells ; the capsule also is usually 

 more inclined and curved, the branches more slender, attenuated, and flagelliform, the 

 stem-leaves as a rule wider and more acuminate ; these last characters are however 

 less constant. Some forms are somewhat like Bi achythecium caspilosum, but the 

 areolation is quite different in the two. Pterogonium gracile differs in the more 

 regularly terete branches with wider, more closely imbricated, two-nerved leaves. 



A large form with obtuse, julaceous branches is known as the var. robmtum 

 B. & S. The var. minus described above appears more worthy of notice, differing as 

 it does from the type not only in the small size, but in the distinctly laxer cells. 



108. PLEUROPUS Griff. 

 (Homalothecium B. &* S., plur. auct.) 



Primary stems more or less creeping, not stoloniform, with 

 numerous irregular branches. Leaves ovate-lanceolate or 



