300 BRYOPHYTA OF S. RHODESIA. 



in which it takes its rise. These considerations quite explain the 

 comparative poverty of the bryophytic vegetation of what might 

 have been expected to be a specially rich locality. 



The other consideration on which I base my expectation that 

 no large additions must be expected to the number of species 

 contained in the following list is that derived from a comparison 

 of the collections made by Dr. Sim and Prof. Wager in traversing 

 practically the same ground in 1920. 



The number of determinable gatherings made by Dr. Sim in 

 this area amounted to about 220, comprising 80 species. Prof. 

 Wager's gatherings (from Matopos and Victoria Falls) numbered 

 25, comprising 20 species, of which only five are additional to 

 Dr. Sim's species, the remaining 15 being common to both lists. 



Now, if the moss flora of the district were a comparatively rich 

 one, and Dr. Sim's 80 species represented only a small percentage 

 of the actual flora of these localities, it is extremely unlikely that 

 only 25 per cent, of Prof. Wager's would be different, and 75 

 per cent, common to both; and it appears to me highly probable 

 that these 80 species represent a quite high percentage of the 

 whole moss flora. Of the 13 species collected by Prof. Wager 

 about the Victoria Falls, only two were different from those col- 

 lected there by Dr. Sim. 



There is always a possibility, in a district under these climatic 

 conditions, of a number of short-lived, minute annual species 

 occurring, and only to be found for a short period after a rainy 

 season, and therefore easily overlooked, or quite absent during a 

 great part of the year. During the last few years Prof. Wager's 

 collections have revealed several such in different parts of South 

 Africa, representing three or four at present undescribed genera, 

 mostly of the Funariaceae, and mostly showing an adaptation to 

 distinctly xerophytic conditions. These, however, should they, 

 or other similar species, occur in Rhodesia, are not likely to enrich 

 the moss flora to any great extent numerically, however great their 

 interest from a biological and taxonomic viewpoint. 



I have added to the list of Rhodesian mosses a short account 

 of some mosses from Portuguese Gaza-Land, containing a few 

 species of exceptional interest. 



Types of new species, unless otherwise described, are in my 

 herbarium. 



The mosses collected may now be systematically described. 

 The following abbreviations are used: St. = sterile, otherwise 

 the specimens are to be taken as fruiting; alt. = altitude. 

 References thus — (3) — are to the bibliography at the end of the 

 paper. 



DlCRANACEAE. 



Trematodon intermedins Welw. and Duby. — On moist sandy 

 river bank, alt, 5,000 feet, Salisbury (Eyles, 2286) ; Zimbabwe, 

 alt, 3,000 feet (Sim, 8826, 8835, 8836); 8826 was corticolous, a 

 curious condition for a Trematodon. 



