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 historj'' of rock 

 and fossil, of hill and lake, and, indeed, of the world itself. 



A Monograph of the Recent British Ostracoda. By George 

 Stewardson Brady, Esq. (Trans. Linn. Soc. vol. xxvi.) 



The 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 jjages, 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 MoUusca 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 Cy there 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 

 subaerial 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, llobertson, &c. col- 

 lecting the recent forms, and Messrs. Crosskey, llobertson, &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 



