130 Bibliographical Notices. 



teeth like Volutida, which are broad, lunate, with nine small, 

 conical, rather distant, transparent denticles on its front edge. 

 Valuta ( Vespertilio) has a single series of three-toothed teeth on 

 the tongue like Yetus and Cijmbium, but the central toothlet is 

 much longer than the lateral ones. 



BIBLIOGRAPHICAL NOTICES. 



Systeme Silurien du Centre de la BoMme. 1^'« partie, Recherches 

 Paleontologiques. Trilobites, par J. Barrande. 2 vols. 4to. 



The history of the palaeozoic formations, both as regards the deve- 

 lopment of the organic life of the period and the physical conditions 

 under which they were accumulated, appears almost to be more 

 clearly revealed to us than that of the more recent accumulations of 

 the later tertiary period. That a knowledge of the primaeval fauna 

 of our planet should be invested with peculiar interest to the zoo- 

 geologist can scarcely be doubted, either in its relation to existing 

 nature, or as pointing out to us the peculiar types of the earliest 

 forms of animal existence. But few years have elapsed since a vast 

 portion of the earlier fossiliferous rocks were classed under the names 

 of greywacke and clay-slate, and were considered entirely destitute of 

 organic forms. Traces of them were, however, discovered in the 

 Scottish series by the acute geologist Hutton, and other observers, 

 as Lhwyd, &c., bad also noticed them in some localities. From the 

 comparative rarity of the fossil organisms in the palaeozoic forma- 

 tions known at that period, they could not have been used as a 

 means of distinguishing the different members of the series, nor 

 indeed was the attempt made so to classify them ; for the great prin- 

 ciple of characteristic fossils, subsequently enunciated by W. Smith, 

 was applied chiefly to the secondary group of rocks. Little, bow- 

 ever, was effected in the classification of these older greywacke rocks 

 until the border counties of England and Wales and a portion of the 

 Principality itself was made the special object of some years' study 

 by Sir R. Murchison, who, " par ses conquetes sur la unit du temps," 

 first initiated us vdtb a knowledge of the earlier palaeozoic epoch, 

 comprising the Silurian system. From that period the active re- 

 searches of geologists have demonstrated the existence of this group 

 throughout large portions of the globe, characterized on the whole 

 by similar forms of organic life, although, as would naturally be 

 expected, modified in the subdivisions by local peculiarities. Since 

 the publication of the 'Silurian System,' large and expensive works on 

 the subject have been issued from the presses of America and Europe, 

 and Siluria seems to be singularly fortunate in the zeal and liberality 

 of her illustrators. Among the more remarkable and interesting is 

 the magnificent volume by M. Barrande. A native of France, and 

 formerly tutor to the Comte de Chambord, to whom the work is 

 dedicated, M. Barrande has, from circumstances, resided for twenty 

 years on the Silurian soil of Bohemia. Commencing his researches 



