THE student's HANDBOOK OF BRITISH MOSSES. 515 



primary division into Acrocarpi and Pleurocarpi, to which they have 

 been accustomed, is abandoned, they will yet find the Pleurocarpi 

 all together at the end of the list. They must, however, look for 

 the GriminiacciE earlier in the list, and no longer in the neighbour- 

 hood of the Orthotrichaci'dc. The cleistocarpous forms are distributed 

 and placed in those orders to which they show vegetative affinity. 

 Modern researches into the peristome have led to the interesting 

 speculation that the differentiation of most types of sporogonium 

 must have been completed before the elaboration of the oophyte (or 

 vegetative part) into stem and leaf began. Thus the primeval type 

 of Moss, consisting principally of protonema and fruit, is indicated 

 to us by that curious survival, Buxhaumia [Handbook, p. 47). 



Against the synonymy of the species it must be urged that it is 

 open to objection on the score of excessive brevity in being limited 

 to the original name of the plant, together with the subsequent 

 names adopted by Schimper and Braithwaite — and by Lindberg in 

 the case of the Pleurocarpi, on the presumption that Braithwaite 

 will extend the Lindbergian notation to this group. Tliis brief 

 synonymy may perhaps satisfy the beginner. But Mr. Dixon should 

 have borne in mmd that his new Handbook is the only complete and 

 adequate modern treatment of our Mosses, and as such will replace 

 Wilson's Brijolonia Britannica (1855), our old standard work with 

 its now archaic nomenclature. Hence he should have arranged for 

 a ready reference from the one book to the other. For, as it is, the 

 inexperienced student will find no direct connecting link between 

 the OUgotrichuiii incurvum and Cylindrothecium concinnum of the 

 newer book and the 0. hercynicum and C. Monta/piei of the older. 

 Again, the species of Webera are only to be collated with the 

 corresponding species of Bryum in the "Bryologia" indirectly 

 through the Pohlia synonyms which are common to both books. 

 Similarly, in cases of Ceratodon cylindricus, Bryum deuiissunt, Iso- 

 thecium alopecurum, Pteroyonium filiforme, Leskea rtifescens of the 

 "Bryologia," which have to be traced through synonyms to their 

 equivalents in the Handbook. The few additions necessary for 

 removing such defects would have increased Mr, Dixon's text to an 

 inappreciable extent, and would have been of great assistance to 

 the old-fashioned Moss- student. 



The distribution of the species Mr. Dixon has been constrained 

 to limit to broad generalized statements for two reasons — lack of 

 materials for drawing out a complete list of localities, and lack of 

 space to print it. But he gives the localities of the rarer species. 



One new species — Fontinalis Dixoni Cardot — makes its debut in 

 the Handbook, and one new subspecies — F'. dolosa Cardot ; and 

 there are six new varieties, to four of which Mr. Dixon is godfather. 

 Attention may be called to the almost simultaneous publication of 

 descriptions of F'oiitinalis Dixoni and F. dolosa by Cardot himself 

 in the Fievue Bryoloyique (1896, pp. 70 & 68). There F. dolosa ranks 

 as a species. 



Some changes of generic nomenclature call for remark — the 

 substitution of Weisia in an extended sense and Trichostomum for 

 Mollia, of Forotrichum for Thamnixim, and of Pleuropus for Homalo- 



