NANOMITRIUM. 267 



A very curious plant, quite unlike any other of our species of moss, though 

 resembling Catoscopium in the form of the fruit. 



57. NANOMITRIUM Lindb. 



Resembling Ephemerum, but differing in the absence of a 

 spore-sac, the capsule smaller and almost entirely without 

 apiculus, and the very minute calyptra. Leaves laxly areolated, 

 nerveless. 



The plants included under this genus, though superficially 

 resembling Ephemerum, are rightly separated on account of the 

 above structural differences of some considerable importance. 

 In Ephemerum the capsule is always more or less differentiated 

 into outer case and spore-sac, the enveloping membrane con- 

 sisting at least of two layers ; in Nanomitrium there is only a 

 single layer of cells, thus representing an even simpler form than 

 Archidium ; and the only approach to an apiculus is a single cell, 

 or at the most three or four, forming a slight thickening at. the 

 summit of the capsule. 



1. Nanomitrium tenerum Lindb. (Phascum tenerum Bruch ; 

 Ephemerum tenerum CM., Schp. Syn.) (Tab. XXXVII. F.). 



Plants very minute, on a persistent protonema. Leaves few, 

 ovate-lanceolate, tapering, nerveless, entire or very slightly and 

 obtusely serrate above ; cells large, rectangular- rhomboid. Cap- 

 sule immersed on a very short, slender seta, almost globose, 

 hardly apiculate, cleistocarpous, pale brown ; calyptra very 

 minute ; spores small, 24-30 p, sub-tetrahedral. Usually 

 synoicous. 



Hab. On mud taken from a fish-pond, near Hurstpierpoint, Sussex (Mitten, 

 1854). Fr. late autumn. 



This very minute plant has never been found again in Britain since its first 

 discovery by Mitten ; the stems are usually more crowded than in E. serratum, and 

 extend over some considerable space. The nerveless leaves distinguish it from all the 

 species of Ephemerum but E. serratum and its sub-species E. intermedium, the nerve 

 of which is sometimes very indistinct ; the almost entire leaves will separate it from 

 these, as will also the small spores and pale brown, not bright reddish, capsule. The 

 inflorescence is also distinct. 



58. EPHEMERUM Hampe. 



Minute terrestrial plants developed on a persistent, much 

 branched, green protonema. Leaves more or less ovate- 

 lanceolate, usually tapering, with rather lax areolation, more or 

 less rhomboid. Capsule immersed, cleistocarpous, rounded, 



