>'EW BKTTTSH SPHAGNA 187 



a.cuminati saepe intorti, folia eorum plus minus imbrieata permagna, 

 quasi 3-3 5 mm. longa. 



Throvvleigh, South Devonshire, 1918, W. It. SJierrin. 



Mr. Sherrin's specimens are about 16 cm. high, stained in the 

 upper part of a deep, almost blackish, violet colour, and differ 

 materially from the var. ochr ace o- viol usee ns in the imbricate and 

 much larger branch-leaves. Both in colour and habit it is a striking 

 form. 



In April last the Rev. C. H. Binstead collected on Cefn Hill, 

 Herefordshire, an interesting Sphagnum of the group Subsecunda, 

 which was sent to me for examination by Miss Armitage. It was 

 found to differ from any of the British species of that group, but 

 rather to form a connecting-link between S. hercynicum Warnst. and 

 $. inundatum Warnst. The latter is a common and very widely 

 distributed member of the group, but the former is a little-known 

 continental species which has not hitherto been detected in Britain. 

 It was described by Warnstorf from material collected in the Harz 

 Province by Dr. Huber in September 1884. The exact habitat 

 appears to be unknown, and it has not. so far as 1 am aware, been 

 been found since, either in the original locality or elsewhere. In the 

 Warnstorfian arrangement it is placed between 8. subsecundum Nees 

 and 8. inunda turn Warnst.. and, for this group of what may be called 

 "small species," it exhibits very distinctive characters, which entitle it 

 to separation. The cells of the stem-leaves are multiporose on both 

 sides, those of the branch-leaves on the outer surface only. But in 

 both types of leaf, in addition to the usual commissural pores of this 

 group, are to be found smaller perforations (winzige Locher), which 

 are very distinctive. They occur either scattered or in one (rarely 

 two) row in mid-cell between the rows of commissural pores. 

 Another and perhaps more striking feature is the structure of the 

 hyalodermis of the stem. The enlarged cells are in one layer. In 

 transverse section, instead of the usual subrotund polygonal outline of 

 neighbouring species, they are elliptical and transversely elongate, 

 and their walls are described as strongly incrassate. 



As Mr. Binstead's plant has the pore-structure of S. hercynicum, 

 one hesitates to place it under 8. inundatum, especially as the 

 examination of very many examples of our ordinary plant have been 

 made without the disclosure of any small pores situated as in S. her- 

 cynicum. Very rarely the stem-leaves of 8. inundatum show, on the 

 outer side of one or two of the cells near the apex, a few ordinary 

 pores in mid-cell, but in such cases the commissural pores disappear. 

 .The hyalodermis of the Cefn plant, moreover, shows cells which are 

 elliptical in cross-section, usually twice and at times thrice as long 

 as wide. They differ from those of typical 8. hercynicum, as figured 

 by Warnstorf (vide Sphagnologia Universalis, 1911, p. 327, fig. 55), 

 in their much thinner walls. 



It seems so universal a rule for the enlarged epidermal cells of 

 both Sphagna and true Mosses to have thin -walled cells, that one is 

 led to suspect that the very stout walls attributed to those of 

 S. hercynicum may be pathological. If normal, their structure is so 



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