373 
folded position. In all cases of reduction, life-size drawings have 
been employed. The magnification of such minute parts as 
sporanges, akenes, seed-coats and appendages is a feature of the 
very highest importance, and one the educational influence of 
which can hardly be over-estimated. Good instances are the 
fruits of the Potamogetons and dissections of the column in Orchida- 
_ ceae. The reduction is conspicuously indicated beside the gen- 
eral illustrations; the degree of magnification of the minuter parts 
is not stated, being considered unnecessary; but we regret the 
omission, or, at least, that it was not made clear that the same de- 
gree was used in illustrating the same organ throughout a group. 
The work upon the illustrations, both drawing and engrav- 
ing, is of the very highest quality, and a remarkable degree of 
naturalness has in most cases been attained. In many cases, as, 
for instance, in that of Xyris torta, the figures are exceedingly 
beautiful. Drawn usually from herbarium specimens, the figures 
have afterward been compared as often as possible with the living 
Plants. To have drawn all the figures from life, would, doubtless, 
have still further improved the appearances, but this was ob- 
viously impossible. 
Natural considerations, which have been allowed to control 
the entire planning of the work, are manifest in the choice of 
the boundaries selected for the flora. Even the announced limits 
are Over-stepped when necessary to complete a natural region, as 
in the inclusion of the extra-limital portions of Nebraska. That 
the relations between geography and botany have been attentively 
Studied is evidenced in more than one way. Both local cata- 
logues and local herbaria have been thoroughly searched to de- 
termine the precise range-limits, and great care has been exercised 
in indicating clearly the habitats of the species. In no preceding 
work has the subject of range been so well elaborated. We find 
in this work, moreover, about the first systematic attempt to give 
the altitudinal distribution. So little attention has been paid by 
Collectors to this important subject that the information here ac- 
cumulated by Dr. Britton can hardly be regarded as more thana 
Working basis, but as such its value will prove very great. Not 
the least valuable of the geographical features is the statement, in 
a general way, of the extra-territorial ranges of the species. Hav- 
