PLAGIOTHECIUM. 431 



From Amblystegium the present genus differs in the longer, 

 more rhomboid areolation, the nerve always double or wanting, 

 the complanate or secund arrangement of the leaves, and the lid 

 frequently longly acuminate and acute. 



./Ls. with angular cells enlarged, more or less decurrent 2 



\Ls. without enlarged angular cells 7 



/Ls. over 1 line long, strongly complanate 3 



\Ls. under 1 line long, indistinctly complanate or subsecund 5 



/Ls. transversely undulate, pale 7. undulatum 



* \Ls. not undulate 4 



{Ls. glossy when dry ; cells 10-12 /* wide ; lid conical-acuminate 

 6. denticulatum 

 Ls. darker, shrinking, hardly glossy when dry ; cells 15-18 p wide ; lid rostrate 

 6*. sylvaticum 



/Ls. with serrulate acumen ; capsule striated j. striatellum 



5\Ls. entire; capsule smooth 6 



,/Ls. complanate, acuminate 8. latebricola 



\Ls. sub-secund, scarcely acuminate 9. demissum 



/Ls. strongly complanate ; plant in flattened depressed tufts 8 



' \Ls. more or less secund, or indistinctly complanate 9 



o/Ls. contracted to a fine acumen, with a few distant teeth 2. Borrerianum 



\Ls. acute, scarcely acuminate, entire or finely serrulate 1. depressum 



with long serrulate acumen 4. siksiacum 



entire .3. pulckellum 



9 



/Ls. 

 \Ls. 



1. Plagiothecium depressum Dixon (Hypnum depressum 



Bruch ; Rhynchostegium depressum B. & S., Schp. Syn. ; 



Isopterygium depressum. Mitt.) (Tab. LV. C). 



In smooth, shining, close tufts of a bright or golden green ; 

 branches slender, procumbent, almost simple, short. Leaves not 

 decurrent, sub-distichous, somewhat depressed on each side of the 

 branches in two regular rows, or nearly complanate ; not 

 crowded, hardly altered when dry, erecto-patent, oval-oblong, 

 acute or shortly acuminate, concave, faintly denticulate in the 

 upper half ; nerve very short and double, or none; cells linear- 

 rhomboid, tapering at ends, 6-10 times as long as broad, very 

 chlorophyllose ; laxer and more pellucid at base, the angular 

 hardly distinct from the other basal cells. Seta short ; capsule 

 oblong, lid longly and finely acuminate. Dioicous. 



Hab. Foot of trees and shaded rocks ; not common. Fr. very rare, winter. 



Much resembling Eurh. confertum and other mosses in general aspect, form of leaf, 

 etc., this species may be known from all the species of the previous genus by its 

 nerveless or shortly two-nerved leaves, and also by its smooth flat tufts with nearly 

 complanate, parallel branches ; from Plag. Borrerianum, which somewhat resembles 

 it, it is known by the less pointed leaves with wider areolation ; Plag. denticulatum 

 has almost always larger leaves, with larger cells, and the leaves are decurrent 

 and have the margin recurved towards base. Plag. demissum has quite different 

 areolation, especially at the base, and is autoicous ; and the habit is quite distinct. 



