246 The American Naturalist. [April, 
In this volume, the author, who has long been favorably known 
as a student of the Rusts more particularly, takes up the vari- 
ous parts of his subject in the following order, viz., Biology 
of the Uredineae ; Mycelium of the Uredineae ; Spermogonia 
and the so-called Spermatia ; yEcidiospores ; Uredospores ; 
Teleutospores; Heteroecism ; Mycelium of the Ustilagineae ; 
Formation of the Teleutospores of the Ustilagineae; Germina- 
tion of the Teleutospores of the Ustilagineae ; Infection of the 
Host-plants by the Ustilagineae ; Spore-Culture ; The Arti- 
ficial Infection of Plants. After this follow the systematic 
portions including nearly two hundred pages of generic and 
specific descriptions. 
Descriptions, synonymy and references to literature and ex- 
siccati are well worked out. All measurements (which are very 
generally given) are in micromillimetres. Many biological 
notes are given after the descriptions, thus adding much to the 
value of the work. 
The genus Uromyces is subdivided as follows into artificial 
subgenera: 
I. Euuromyces : A. Auteuuromyces represented by ii species. 
B. Heteruromyces " 4 ** 
II. Brachyuromyces, <' o " 
III. Hemiuromyces, " 6 '* 
IV. Uromycopsis, '< , 3 " 
V. Micruromyces, •< 4 " 
VI. Lepturomyces, " o " 
Making a total of 28 species. 
The genus Puccinia is similarly subdivided : 
I. Eupuccinia: A. Auteupuccinia represented by 23 species. 
II. Brachypuccinia, «< c " 
III. Hemipuccinia, " 14 
IV. Pucciniopsis, «« 3 «' 
Making a total of 96 species 
The remaining smaller genera are represented as follows: 
Triphragmidium — 2 species; Phragmidium — 9 species; 
Xenodochus — 2 species ; p:ndophyllum — 2 species ; Gymnos- 
porangium — 4 species; Melampsora — 17 species; Coleospo- 
rium — 4 species ; Chrysomyxa — 2 species, and Cronartium — i 
species. In addition there are descriptions of imperfect forms 
as follows: Uredo— 11 ; Caeoma— 6; ^cidium— 21. There 
are thus descriptions of 167 genuine species, and 38 imperfect 
