452 Bibliographical Notices. 
both geologist and tourist will find it a useful book, suggestive of 
valuable thoughts for the speculative, and of good lines of research 
for the practical man—helping, in the study, to the memory of 
former labours in this region, and, in the field, showing where whole- 
some pleasure may be gleaned in hunting out the history of rock 
and fossil, of hill and lake, and, indeed, of the world itself. 
A Monograph of the Recent British Ostracoda. By Grorer 
Srewarpson Brapy, Esq. (Trans. Linn. Soc. vol. xxvi.) 
Tue whole of the last-issued Part of the Linnean Transactions is 
occupied by the monograph which we are about to notice, and which 
extends to 143 pages, illustrated by nineteen plates. 
We have here a most valuable contribution to the history and eluci- 
dation of the Ostracoda. The study of this section of the Crustacea 
has, both on the Continent and in the British Islands, been recently 
attracting much greater notice, and, we venture to prophecy, is de- 
stined to occupy a much larger share of the attention both of zoolo- 
gists and geologists than it has hitherto done. This is the only 
order of the Crustacea the remains of which have been found fossil 
throughout a long series of beds in considerable abundance; and 
they are likely, when more diligently searched for, hereafter to 
render important service in assisting the geologist in the classifica- 
tion and sequence of strata. They present certain advantages for 
this purpose over the Mollusca and other larger organisms, because 
the small and generally strong valves of their minute carapaces will 
often escape destruction when it fares badly with their larger 
brethren. For example, glacial action, which will grind to pieces 
all univalve and bivalve shells, may be expected to leave unharmed 
the Cythere or the Bairdia—just in the same way as while we crush 
the snail to atoms under our foot, the little ant which was there at 
the same time, so far from objecting to the operation, turns smack- 
ing his lips to the dainty morsel which we leave him to enjoy. A 
more careful washing of glacial clays and attentive search for the 
Ostracoda which they may contain will be found no unimportant 
step in the determination of the circumstances under which a parti- 
cular bed was deposited, as showing whether it owes its origin to 
subaérial or true glacial ice, or was a submarine or icebergal depo- 
sit. Indeed, so abundant are fossil specimens, that with our present 
workers in the field, Messrs. Brady, Norman, Robertson, &c. col- 
lecting the recent forms, and Messrs. Crosskey, Robertson, &c. the 
Tertiary and, more especially, Quaternary forms, it has become a 
mere toss-up whether a species shall first be found fossil and then 
recent, or vice versd. Of the species described by Mr. Brady, no less 
than fifty-six marine and six freshwater species have already been 
met with fossil in the glacial and other more recent deposits ; and 
what makes this the more striking, as showing how completely this 
study is even now in its infancy, is the fact that no less than forty- 
three out of the fifty-six marine species referred to, and which are 
