562 
LIST OF NORFOLK MOSSES. 
Webera carnea, Schp. 28. Rojdon Common (J. S.). 
Thornham (W. E. T.). 
Bryum mamillatum, Lindb. 2S. Among Juncus gerardi on 
low ground between sand dunes. Hunstanton 
Links, May, 1902. Rev. W. E. Thompson. 
As this is the first record of this very rare species in Britain it 
deserves a somewhat extended notice. Mr. Thompson sent me the 
plant in June, for determination. I could not make it agree with any 
of our British species, and on comparing it witli the descriptions of 
continental species I could find none with which it agreed but 
Bryum mamillatum , Lindb., a species only recorded hitherto from 
the sandy shores of the islands of Gothland and Aland in the 
Baltic. On comparing it with my specimens gathered there by 
Bomansson I could detect only slight and as it seemed to me com- 
paratively unimportant differences. In order to clear up any doubt 
I sent specimens to Dr. Hagen, the acknowledged authority on, at 
any rate, the northern species of this very critical group. Dr. 
Hagen was at first inclined to think the differences of somewhat 
greater importance, but upon a further study of fresh material of 
B. mamillatum from its Scandinavian stations he recognised that 
its variations were sufficiently extended to include our plant, so 
that its identification with B. mamillatum may be looked upon 
as unquestioned. I am describing and figuring it in a second 
edition of the ‘ Student’s Handbook of British Mosses ’ now in 
preparation, and it is scarcely needful to give a full diagnosis here; 
but some notes as to its distinguishing characters may be worth 
giving. Systematically it holds a position of somewhat peculiar 
interest, as it affords a link in some degree between the sections 
Ptychostomum and Cladodium in the genus Bryum. In each of 
these sections the peristome is imperfect, the cilia of the inner 
peristome being more or less undeveloped, sometimes quite 
rudimentary or wanting, or if longer, always without the transverse 
appendages or bars which characterise the fully developed peristome 
of Eu-bryum and of most Hypnaceie ; while the inner peristome is 
usually more or less united with the outer. The two sections 
differ from one another in the structure of the inner surface of the 
teeth of the outer peristome. This surface in Cladodium consists 
of rectangular plates set one above another, and separated by 
transverse divisions or bars which are strongly thickened, projecting 
