DICRANACEAE. 59 
thin seta, also black (Mitten, it may be observed, describes the seta as 
* erassiusculo wg The figure of ep of D. tenuifolium, Fl. Antarct., 
at the British Museum shows a much more robust bright-bronze- 
coloured, somewhat glossy plant, with longer leaves strongly and regularly 
circinate, and a very appreciably larger brown capsule on a much stouter, 
also brown, seta. Except in these characters of size and colour and of leaf- 
direction, the two plants are identical, but the differences described are so 
deseribing B. robusta, which he compares with B. stricta (H. f. & W.), a 
species certainly not nearly so closely alli 
If it had been a question of these two specimens alone, I should have 
undoubtedly felt that the Australian plant, and Brown’s Waimakariri 
D. rupestre (D. circinatum in herb.), which is certainly the same, deserved 
varietal rank at least. But a comparison of other specimens showed 
that it was impossible to create even a variety on any defined lines. 
0 
gq. sp ew., ; i 
det. Mitten, Australian Alps, 6,000 ft., No. 12, Dr. Miiller, 1855,” 
is compared. This, which was probabl part of F. Miiller’s original 
gathering of B. robusta, is just intermediate in size and habit between 
the two; it has the colour of robusta, but is more slender, with the 
foliation sabroncne that of tenuifolia. There are no “geste A further 
specimen, of the same locality and date, No. n Herb. Hook., in 
rich fruit, has all the characters of robusta, but has a very considerable 
degree of variation in the size of capsule and thickness of seta, though both 
are always greater than in B. tenwifolia type. B. tenwifolia, Mount Wel- 
lington, Tasmania, leg. Weymouth, 1888, in Herb. Kew. (no doubt the 
original of B. Wellingtonii C. M., Gen. Muse. Fr., which otherwise I have 
not seen), is robusta in the colour ont size, and in the colour and size of the 
capsules, but the brown setae are in no way stouter than in typical tenuifolia. 
D. tenu ifolium, Tasmania, Archer, det. Mitten, also at Kew, is near re 
type in size of plants and of capsule, but a little larger and golde n 
colour ; it is, m fact, exactly intermediate between the types af the two 
supposed species 
D. collinum R. Br. ter. and D. Walkeri in Brown’s herbarium are perfectly 
black in both leaves and fruit, with the small eapetiies of tenuifolia, but are 
far more robust plants than tenwifolia type, fully agreeing in size, and length 
of leaf, with B. robusta, but with the leaves rather faleate than circinate, 
though a stem here and there shows the leaves rather markedly circinate. 
_— also, therefore, are strikingly intermediate between the two extreme 
form: 
There: is little doubt, therefore, that the two are but extreme conditions 
of one species, and the colour at least is probably due simply to the environ- 
ment. It is a frequent experience in regard to alpine-arctic mosses that 
h 
considerable period with snow, they tend to me black in hue. This 
is a marked feature with some of the European high alpine forms of Philo- 
