340 SUMMAKV OF CUEKENT RESEARCHES RKLATING TO 



the Chicago region, under two headings — xerarch and hydrarch succes- 

 sions. In Table I. is shown the succession of the fifteen principal 

 mosses present in the xerarch series of the sand dunes, through the 

 five stages— cotton-wood, pine, transition pine-oak, oak, beech-maple. 

 Table II. represents the hvdrarch succession from open water of lagoons 

 and ponds, through the stages — sedge mat, tamaracks, swamp forest, to 

 the beech-maple forest ; and here twenty mosses are concerned. In the 

 successions on sand, mosses are most abundant in number and quantity 

 in the pine stage and decrease in and after the oak stage. In the 

 hydrarch successions the greatest dominance of mosses is usually in the 

 swamp or bog forest (tamaracks). Mosses are important pioneers on 

 bare rock surfaces, and continue abundant far into the forest association. 

 They are of the greatest value from an economic standpoint. They are 

 soil-formers and provide favourable habitats for germination of higher 

 plants. They assist largely in forming the surface mat over deep lakes 

 and in filling up shallow waters. They may help to build up tufa, and 

 to make floating islands. They conserve moisture and give it out 

 slowly, thus checking the formation of disastrous floods. They prevent 

 erosion of clay or sand surfaces. A. G. 



Hymen ostomum in North America. — A. LeRoy x\xdrews 

 {Bryologist, 1020, 23, 28-31). A discussion of the delimitation of the 

 genus. There is a perplexing group of closely related species which 

 have been divided among the genera Astomum, Hymenosiomum and 

 Weisia. Alike in their garaetophy tes and with sporophy tes representing 

 a very close gradation of forms, these plants make the limitation of 

 species and genera a matter of debate. Hymenostomum rostellatwu is 

 as good an Astomum as a Hymenostomum. After citing instances of 

 confusion, natural affinities, attempted revisions of genera, he proposes 

 to retain the name Hympiiostomum for tbe group, the type being 

 H. microstomum (Hedw.) 11. Br., and to employ three sub-genera — 

 Astomum^ Elihymenostomum, Weisia, which normally are respectively 

 cleistocarpous, hymenostomous and peristomate. A. G. 



New and Interesting' South African Mosses. — H. X. Dixon 

 {Trans. Roy. Soc. South Africa, 1920, 8, 170-224, 2 pis.). An account 

 of a large number of mosses from South Africa collected mainly by 

 H. A. Wager, T. K. Sim, J. Henderson, including about two dozen 

 species new to science, and valuable critical notes on many species which 

 required illumination — e.g. C'aj/ipijlojnis inchangae, the specific name of 

 which has l)een rendered by various authors as Inczangae, Incrangae, 

 Incrangse, Imerangse. It is shown that the water moss Fissidens 

 julianus is a widely distributed species, and that F. Berterii, F. DiUenii 

 (both from temperate South America), /'. capensis and F. 3IueJleri 

 (Australia) cannot be separated from it. In half a dozen other cases 

 the identity of Cape species with previously described European species 

 is demonstrated. A. G. 



Mosses of Madeira.— A Luisier {Broteria, 1010, 17, 28-6G, 1 pL). 

 Continuation of an historical and systematic account of the moss-flora of 

 Madeira, with some critical notes, descriptions and a few figures. A. G. 



