REVIEWS. 
A Monograph of the Fresh-water Polyzoa. By Guo. J. 
Auman, M.D., F.R.S., &c., Regius Professor of Natural 
History in the University of Edimburgh. 
To the well-known and invaluable series of Monographs 
by Alder and Hancock, Forbes, Baird, and Darwin, published 
under the auspices of the Ray Society, we have to announce 
the addition of the long-expected work of Professor Allman, 
on the ‘ Fresh-water Polyzoa, including all the known species, 
both British and Foreign.’ 
In this splendid addition to their publications, the Ray 
Society, as in the former, has done excellent service to natural 
history ; for whether we regard the intrmsic interest of the 
subject itself, the complete and exhaustive way in which it has 
been treated, or the beauty and fidelity of the illustrations, 
Professor Allman’s Monograph may well take rank among 
the most important contributions to zoological science that 
have appeared for many years. 
In the preface we are informed, if that were necessary, 
that the work contains the result of many years’ careful 
study, and that in its preparation no trouble has been spared 
to render it as complete as possible, the subjects of which it 
treats having been considered under every point of view of 
which they seemed susceptible—zoographically, zootomically, 
homologically, and historically. All the figures, we further- 
more learn, upon the eleven lithographic plates, have been 
drawn from nature, and contain careful representations of 
of every species seen by the author, and in every case a 
figure is given of the species, both coloured and in its natu- 
ral size and magnified. 
As the number of known species of “ Fresh-water Polyzoa” 
is very small—not amounting to more than twenty-one, 
twelve of which belong to one genus,—it is obvious, that had 
the work been limited to a mere zoographical description of 
them, its bulk would have been very inconsiderable. But of 
the 119 pages of which it consists, 75 are occupied with con- 
siderations involving the Polyzoa in general, though more 
especially directed to those which are peculiar to fresh water. 
It is needless to insist upon the greatly-increased value given 
to the work from this large portion of its contents, for, as 
remarked by Professor Allman, “ the Polyzoa constitute an 
exceedingly natural group, and possess great uniformity of 
