596 General Notes. [July, 
little essay furnishes in a tabular form a synopsis of a chemical 
and microscopical analysis which can, by its aid, be carried out 
with great facility by any person accustomed to such manipula- 
tion and familiar with the appearance of the objects sought for. 
Such a manual should not and cannot be made to take the place 
of more thorough treatises on the same subject, but as an adjunct 
to them it is a great convenience and time-saver, alike to begin- 
ners who are lost in the multiplied details of the larger books and 
need a guide-book to them, and to experienced men of business 
whose crowded time compels them to refresh their memories in 
the easiest possible way. 
flow to See with the Microscope, by J. Edwards Smith, M.D., 
pp. 410, Chicago, 1880.—The most valuable portions of this work 
are the various suggestions in regard to the manipulation of the 
modern wide-angled objectives, which are scattered throughout 
the work, though given more particularly in the form of lessons 
in the latter pages of the book. It is greatly to be regretted that 
the really useful ideas should be buried in such a vast amount of 
personality and of (to say the least) irrelevant discussion. 
fresh-water Rhizopods of North America, by Joseph Leidy, 
M.D., 4to, pp. 324, Washington, 1879, and Synopsis of Fresh-water 
Rhizopods, compiled by Romyn Hitchcock, F.R.MS., PP. 56, 
New York, 1881.—The superb work on Fresh-water Rhizopods 
by Professor Leidy has lately made the study of these organisms 
easy as well as charming. His treatise is a scholarly and digni- 
fied work, upon a class of objects hitherto studied with difficulty 
‘on account of the fragmentary and scattered character of the data 
that were available to students. The present work, published by 
the Department of the Interior as a portion of the U. S. Geologi- 
cal Survey of the Territories, is well printed and sumptuously 
illustrated, and is a credit not only to the author and to the sur- 
vey of which it forms a part, but also to American science. 
upon it, and published it as stated above. Brief descriptions 
of the genera and species are given, with scarcely any var 
will 
of 
engravings of typical species would probably find ready sale 
book. 
