RECENT ADVANCES IN SCIENCE 573 



the surface of the gametophyte. The venter is embedded 

 and terminated by a straight neck of four rows of cells. 



The differences between the prothalli of the two genera 

 mainly depend on the size of the male and female organs, and 

 their relative abundance. 



Taxonomy. — In the September and October numbers of 

 the Naturalist, Mr. D. A. Jones contributes a list of the Mosses 

 and Hepatics of Denbighshire. Of the species and sub-species 

 enumerated, over one hundred are new records for the county 

 and to these must be added some forty additional varieties. 

 Amongst the rarer mosses may be noted Barbula gracilis, 

 Trichostomum crispulum vars. nigro-viride and brevifolium, 

 Encalypta rhabdocarpa and Amblystegium Kochii. The Hepatics 

 include Moerckia Flotowiana, Cephaloziella byssacea v. asperi- 

 folia, C. stellnlifera, C. myriantha, and C. Limprichtii. 



Lists are given of species characteristic of the different 

 geological formations. 



The same author describes and figures several new varieties 

 of Mosses {Journal of Botany, October 191 7), viz. Campylopus 

 setifolius v. intermedins, Bryum pallens v. euryphyllum, Porotri- 

 chum alopecurum v. aridulum, and Pterogonium gracilis v. 

 harlecense. 



In the same journal Mr. Baker contributes an account of 

 the flora of Burnham Beeches, and Dr. Wernham describes 

 a number of new species of tropical American Rubiaceae. 



In the Naturalist for December, Mr. F. A. Lees gives a 

 useful account of the species of Erodium found as colonist-aliens 

 in Yorkshire. 



Ecology. — J. S. Henkel, writing on Forest Progress in the 

 Drakensberg (S.A. Jour. Sci., December 19 16), describes the 

 process of succession from veldt to forest. In the early phases 

 scattered bushes of Protea, together with Cussonia, Celastrus 

 buxifolius,Leucosidea sericea, and Myrsine africana, which appear 

 in the order named, compete with the veldt grasses and by 

 their shade gradually eliminate them. Later as the shrub 

 vegetation increases, lianes and seedlings of various trees 

 appear, and the veldt-grasses become replaced by bush-grasses 

 and ferns. The Leucosidea bushes are suppressed by the forest 

 trees and shrubs, till finally the climax phase is reached in 

 which the prevailing arboreal forms are Podocarpus thunbergii, 

 Olinia cymosa, and Myrsine melanophleas. 



