Dixon: NEw MossEs FROM MALAY PENINSULA 227 
All the allied species of the genus in this region are at once 
known by having the setae either aggregate or much shorter, or 
the capsule narrowly cylindric and distinctly strumose. In 
D. sumatranum Broth. the capsule is suberect, not arcuate, 
and more cylindrical, with a somewhat distinct neck. In the 
present plant there is no trace of struma, and very little of collum. 
Thysanomitrium abbreviatum Dixon sp. nov. (PLATE 3, FIG. 3) 
Habitu T. exasperati, sed caulibus siccis turgide julaceis, et 
propter folia multo breviora subteretibus. Folia eis T. exasperati 
similia sed breviora, apice latiora, obtusa, valde concava, nervo 
omnino alieno, basi 1/5—1/4 folii latitudinem aequante, tenerrimo, 
plerumque unistratoso, cellulis 3-4-seriavis medianis tanium bis- 
tratosis, omnibus homogeneis. Caulis unicus fructiferus vel 
masculus juvenis 7. exasperato similis. 
HAB. Summit of Gunong Tahan, Pahang, alt. circa 7000 
ft.; Ridley (1012). 
This and the following species are very remarkable; with 
nearly all the characters of T. exasperatum,and T. umbellatum 
respectively, they present a nerve structure which is totally 
different, so much so as to suggest even a generic distinction. 
In those species, as is well known, the broad nerve, though thin, 
consists of at least three elements throughout the breadth, viz., 
a central layer of guide-cells, and both a ventral and dorsal 
layer of stereid ones, with occasionally outside these a slightly © 
differentiated superficial layer of external cells. In the two 
species under consideration the nerve, while broad, consists for 
the greater part of its width of a single layer of small cells, 
scarcely distinguishable in section from those of the lamina 
(though quite distinct, owing to their form, from these when 
viewed from the front or back); the middle part of the nerve 
alone showing a double layer, but still of the same form of cells, 
and only extending for the width of three or four rows. 
The leaves are shorter, more closely imbricated and appressed 
when dry, so that the stems are more terete and julaceous than 
occurs, unless very rarely, in T. exasperaium. 
Thysanomitrium Ridleyi Dixon sp. nov. (PLATE 3, FIG. 4) 
Praecedenti (IT. abbreviatum) peraffine; differt tantum foliis 
bilo longiusculo hyalino sublaevi abrupte terminatis. 
