176 Recent Literature. [ March, 
sour, juicy, refreshing stems might often be very serviceable to 
travelers if acquainted with its properties. 
From the summit of the Burros the eastward slope stretching 
away for thirty miles, to the base of the Santa Ritas, descends so 
very gradually that the whole tract appears more like an elevated 
plain than like a mountain slope. The vegetation is that of the 
higher south-western plains, there being no trees, few bushes, in 
fact not much but grasses and numerous species of the vast genus 
Astragalus. The Astragali that grow here (A. mollissimus Torr.; 
A. missouriensis Nutt.; A. humistratus Gray; A. cobrensis Gray ; 
A, shortianus Nutt., and A. nuttallianus Gray) are mostly very 
handsome sorts, with more or less white, silky foliage, and fine 
racemes of rich violet, or pink, or purple flowers, quite different 
from the rattle-podded things of the same genus which occupy 
the plains at the western base of this same range of hills. 
Pe kanama h 2 
RECENT LITERATURE. 
LeConte’s Grotocy.'—The body of this work is divided into 
three parts, treating respectively of dynamical, structural and 
historical geology. The author devotes the large space of 160 
pages to the consideration of the dynamical agencies concerned 
in producing crust-modification. Atmospheric, aqueous, igne- 
ous and organic agencies are successively considered. Er 
sion due to rain and rivers, the action of waves and tides, glacial 
action, chemical agencies, each receive a full share of attention, 
with good illustrations. The subject of earthquakes and volcanoes 
is fully and elaborately discussed and the great geyser district O 
the West receives more attention than has been devoted to it 
ness that will be appreciated by all American students. The 
section devoted to*the consideration of reef-formation is. full of 
- valuable matter with well chosen illustrative diagrams, as is also, 1 
that on faunal and floral distributions. 
_ The hundred pages devoted to structural geology is an unusually 
large proportion for this subject, but the many varieties of fault 
ing and unconformability due to various causes, and which are 
calculated to puzzle the young geologist, require the full elucida- 
tion which they receive in the work. 
