I much regret that, by an oversight, I have omitted to insert var. δ _squarrosulum_ under _Sphagnum cymbifolium_, gathered by my friend Mr. Bagnall, in Sutton Park, Birmingham; and the same locality should be added after _Hypnum aduncum_, _H. Sendtneri_, and _H. intermedium_. I must here express my gratitude and thanks to those gentlemen who have so kindly assisted me in its preparation, both with the loan or gift of specimens of the rarer and newer species, and also for the diagnoses received from several, where specimens were not attainable. Amongst these gentlemen I must specially thank Dr. Hooker for his kind permission to use the Herbarium specimens and Library at Kew, and Mr. J. G. Baker, F.L.S., for his valuable assistance in doing so; also Dr. Braithwaite, F.L.S., Mr. J. Bagnall, of Birmingham; Dr. F. Buchanan White, of Dunkeld; Dr. Fraser, of Wolverhampton; Rev. J. Fergusson, of New Pitsligo; Mr. Carruthers, F.L.S., of British Museum; Mr. G. E. Hunt, of Manchester; Mr. John Sim, of Strachan; Mr. W. Galt, of Edinburgh; M. P. Goulard, of Caen, Calvados; and lastly, all those gentlemen and ladies who so readily came forward as subscribers to the number of upwards of 200, to assist in the publication of the volume. CHAS. P. HOBKIRK. HUDDERSFIELD, _February, 1873_. LIST OF CONTRACTIONS USED IN THIS VOLUME. br. _branches._ br. l. _branch leaves._ cal. calyp. _calyptra._ caps. _capsule._ fem. _female._ fl. _flower._ fr. _fruit or fructification._ infl. _inflorescence._ innov. _innovations._ l. _leaves._ m.m. _millimetres._ ped. _pedicel_ or _seta_. per. perist. _peristome._ per. l. and p. l. _perychætial leaves._ per. teeth. _teeth of peristome._ perig. l. _perigonial leaves._ st. _stem._ st. l. _stem leaves._ NOTICE TO COLLECTORS. It is my intention, as soon as sufficient material can be accumulated, to publish “A Geographical Distribution of the British Mosses,” and, in furtherance of this object, I should esteem it a great favor if all collectors throughout the kingdom would kindly be at the trouble of forwarding to me, as early as convenient, complete lists of the Mosses found by themselves or their friends, in their several districts, with any notes they may think desirable respecting them, and, where possible, the range and habitat of the various species. I feel sure I have only to mention this to ensure an abundant return of information for a work which is really wanted, and shall, so far as any exertions on my part can ensure it, be really valuable. C. P. H.