8 The Mosses Anacalypta and Pottia. 



THE MOSSES ANACALYPTA AND POTTIA. 



BY M. G. CAMPBELL. 



February, with its chilling breezes, its sleety storms, its leafless 

 trees, and its oft snowy lawns, while it seems to freeze the 

 young buds of the tall trees, and hang their boughs with 

 icicles, yet spares the lowly mosses, and gives some of the 

 most minute and delicate strength to ripen their tiny fruits. 



Of these, the genus Anacalypta stands foremost, deriving 

 its name from ava, above, and KaXwrrTos, covered, in allusion to 

 the circumstance that the calyptra remains on the capsule until 

 the spores are perfectly ripe, which is, doubtless, a provision 

 of nature against the inclemency of the season. 



The members of this, like those of its sub-genus Pottia, 

 named in honour of Professor Pott, of Brunswick, are small, 

 chiefly annual or biennial mosses, loosely gregarious, growing 

 upon newly-exposed soil, and occasionally upon walls in low- 

 land districts. The two sections are exceedingly similar in 

 mode of growth, in fruit, in the form and structure of the 

 leaves, and in the inflorescence ; but differ in the Pottias being 

 without a peristome, while the Anacalyptas proper are furnished 

 with a peristome, which consists of a single row of sixteen 

 teeth, united at the base by a narrow membrane, plane, lanceo- 

 late or imperfectly divided into two portions, or perforated ; 

 occasionally, however, incomplete or fragmentary, and without a 

 medial line. The spores, too, are rather smaller than in Pottia. 



On banks and in fields in the middle and south of Britain, 

 those who wish to investigate this interesting group may find 

 the beautiful little Anacalypta Starlceana, {Stark' s Anacalypta) , 

 of which wo give a magnified illustration ; the 

 natural size of the plant being less than one 

 line in height of stem, and, Avhen in fruit, with a 

 seta of about equal length ; but in this, as in 

 other respects, the species is variable, for in the 

 same tuft may bo found specimens with fruit- 

 stalks twice as long as others. It will, however, 

 admirably serve as a type of both sections of this 

 genus; indeed, it has puzzled muscologists to 

 determine to which section it should properly 

 bo given, the presence or absence of a peris- 

 tome being the chief difference between it and 

 Pottia minutula, or the dwarf Pottia, variety 

 conica, which might almost be called a toothless awaoalypta 

 Anacalypta Starheana; and, if we may judge by stabxkana. 

 the variety of names that have been conferred upon it, as 

 A. Starkeana by Nees and Homshuch, Bruch and Schimper ; 



