190 THE BRITISH MOSS-FLORA. 



known to every one who has attempted such work, and to many 

 who have not. Of course, when the material to be examined is 

 Hmited in quantity, the task is comparatively light. But when the 

 region has been well explored, and great masses of material have 

 been collected, when the determinations of one's predecessors have 

 been made either incorrectly or in accordance with the systems of 

 different schools of botanists whose notions of species are as varied 

 as tlieir systems of classification, and when the species themselves 

 are linked together by numerous intermediate forms ; then the task 

 becomes one which should be allotted to the born genius, or, in the 

 absence of such, must be entrusted to some industrious but less 

 transcendently gifted person who by the exercise of infinite care 

 and painstaking may be expected to bring the work eventually to a 

 happy conclusion. 



Now the Mosses of the British Isles have, thanks to the active 

 researches of collectors, accumulated during the present century, 

 and called for a thorough revision. It is much to Dr. Braithwaite's 

 credit that he has already brought to completion the second volume 

 of our standard Moss-Flora, and with it the more difficult and less 

 interesting section of the group, viz., the Acrocarpi, which form 

 about three-fifths of the whole group. The Pleurocaipi alone 

 now require to be monographed ; unless indeed Dr. Braithwaite 

 should think fit to finish the Flora with a new treatment of the 

 S/ihai/)ia, which would be for him a far lighter task than for any 

 other British bryologist, as it would mean only a revision of the 

 critical work he has already published on the subject. 



The present part contains two families — Meeseacea and Mniacea, 

 as to the treatment of which a few remarks may be made. Dr. 

 Braithwaite follows Lindberg in dropping the use of the name 

 Aulacumnium, and breaking the genus into two — Gynmoci/be Fries, 

 with two species {G. pahistris and G. tuxjUla), and Orthopyxis 

 P. Beauv., with one species [O. andro(iyna) . He describes fourteen 

 species of Mniuni, and has drawn some unusually pretty figures of 

 them. He has replaced the earlier name of M. serratiun Schrad. 

 (1791) by M. viaiyinatiun P. Beauv. (1805), either because there is a 

 doubt as to what Schrader's plant really was, or because iiian/inatum 

 was the original specific name under which Dickson put the plant in 

 its original genus — Bryum. Dr. Braithwaite points out the confusion 

 that has prevailed between ill. riparium and M. ortliorlujnchwn, the 

 former of which has laxer leaves with larger cells. The replacement 

 of M. afme Bland. (1804) by M. cuspidatum Neck. (1770) is un- 

 fortunate, as it necessitates a change in the case of another species, 

 viz., from M. cuspidatum Hedw. (1801) to M. silvaticum. Lindb. 

 (1867). Confusion between the two plants is sure to arise. An 

 additional British species is M. Sdiyeri Juratzka, which used to be 

 confused with M. ajfine (3. elatum Br. et Sch. The older name M. 

 pseudupunctatim Br. et Sch. (1843) takes the place of the subsequent 

 M. suhijlohusum of the same authors. 



In the Supplement are four species which are additional to vol. i. 

 These are Catharinea Hansskiwchtii Broth, (not "Hauslaiechtii," as 

 Dr. Braithwaite spells it), MoUia brevifulia Braithw., Barbula 



