BOOKS AND CURRENT LITERATURE 327 



To readers of The Plant World this book will be of particular inter- 

 est in that the habitat is particularly emphasized as of value in classifi- 

 cation. In the keys to the genera the eighteen main headings, set up 

 in black-face type, are subdivisions according to habitat, e.g., Plants 

 growing on the ground, Plants growing on roots or trunks of trees, etc., 

 thus practically classifying the mosses on an ecological basis. Many 

 workers in ecological plant geography have been too prone to only 

 roughly classify, or to leave out altogether from their ecological lists, 

 the names of the smaller mosses: and to such workers we would par- 

 ticularly recommend Mrs. Dunham's book. 



This book will be of value not only to the amateur bryologist and to 

 the ecologist who does not pretend to be a bryologist, but even to the 

 professed bryologist who knows the species as they appear under the 

 microscope. It is essentially a field-book, and the emphasizing by 

 italics of the most prominent naked-eye characters seems, at least to 

 the reviewer, to constitute a most valuable contribution to our bryo- 

 logical literature. The present writer has tested the book on several 

 occasions, both in Pennsylvania and in northwestern Ontario, and the 

 results have been quite satisfactory. 



The book takes up, altogether, 80 genera and about 150 species, the 

 author remarking that: ''The mosses included in the Keys are those 

 that are commonh^ or occasionally collected in the northeastern part 

 of the United States. But the Kej^s really cover a much larger field, 

 many of the mosses being widely distributed, as will be seen by read- 

 ing the range given with each genus or species." With regard to the 

 relative abundance of the various species described, the book would 

 seem to apply more particularly to the New England States, and due 

 allowance should be made for this by those using the book farther to 

 the south or southwest. The species treated in the book comprise 

 probabl}' from one-third to one-half of those in the moss-flora of most 

 localities in the eastern two-thirds of the United States, but in point 

 of relative abundance and of conspicuousness the proportion treated 

 would appear considerably larger. 



As would naturall}' be expected, little or no attempt has been made 

 by Mrs. Dunham to separate the species of genera which embrace 

 minute plants or whose species are separable only by microscopic 

 characters. Among the genera in which little or no attempt has been 

 made to separate the species, the following may be noted: Sphagnum, 

 Andreaea, Fisside7is, Orthotricum, Pylaisia, Leskea, and Thuidium. 



