80 BOTANICAL GAZETTE [JULY 
of the various plant associations agrees very closely in every instance with 
variations in this ratio, the vertical range of littoral species being strictly and 
sometimes very narrowly limited. Strangely enough, practically no species 
is found to be distributed, as so often reported, ‘“‘between tide marks.” The 
data upon the evaporative power of the air are scanty, only going to show that 
it is high, for as the atmometer readings were for a few hours of daylight only, 
no significant comparisons could be made with the data of other observers. 
Aeration due to tidal movements seems to be of some importance, while upon 
variation of salinity, the direct action of rain upon exposed vegetation, and the 
variation in light and their effects few exact data have been obtained as yet, 
but the careful study of the oa ie relative times of. submergence and 
exposure has clearly defined ma t 1 for future investigation. 
This is perhaps the largest va ae from the careful and extended work of 
the authors. 
Little less important than the careful analysis of the factors controlling the 
vegetation is the detailed study of the distribution both of the plant associations 
and of the species composing these associations. The results are expressed 
in several excellent vegetational maps of the entire harbor, of the sand spit, 
and of the estuarial marsh, together with belt transects on a large scale of the 
spit and the marsh. These provide a basis for future studies, two or more 
decades hence, that will certainly do much to give a better understanding of the 
causes and progress of plant succession in this and similar areas. The abun- 
dance of the data, the care with which they have been collected and arranged; 
the number of the maps, diagrams, and tables, and the organization of the 
discussion, are all matters to be highly commended. _The deficiencies and 
omissions are such as are dependent upon the size of the problem and the 
multiplicity of the factors involved, rather than upon the neglect or oversight 
of she investigators, who are inet be congratulated upon their patience and care 
in tion to our knowledge of littoral vegetation.— 
Geo. D. ‘FULLER. 
Taxonomic notes.—BartLeT? has described a new Mexican guayule, 
naming it Parthenium Lloydii, collected by Luoyn in Zacatecas. 
Drxov? has described 10 new species of African mosses, one of which (F. 
W ageri) is made the basis of a new section of Fabronia. He also notes and dis- 
cusses 21 additional rare species. a 
Evans” has described a new species of Metzgeria (M. grandiflora) from the 
Galapagos Islands, included in a collection of liverworts made by ALBAN 
§ BarTLETT, H. H., Parthenium Lloydii, a new Mexican guayule. Torreya 
16:45-46. 1916. 
» Dixon, H. N., New and rare African mosses, from MirTen’s herbarium and other 
sources. Bull. Torr. Bot. Club 43:63-81. pl. 1. 1916. 
10 Evans, A. W., A new species of Metzgeria from the Galapagos Islands. Torreya 
16:67-70. figs. 5. 1916. 
