Beviews — 77ie Fauna and Flora of the Silurian Period, 521 



pared with each other and with existing forms, that evidently the 

 authors approach dangerous ground in attempting to define them, 

 and are at a loss to find distinctive names for their species. Still, it 

 is evident that these old forms must be recognized and catalogued ; 

 and whether or no some of them astonish us by their apparent 

 similarity to (and almost identity with) living species, we are glad 

 to see geologists and naturalists attempting to define them, with 

 creditable industry and acumen in working out their relationships, 

 and bringing artistic skill to bear in their delineation. 



III. — Thesaurus Siluricus — The Fauna and Flora of the 

 Silurian Period. By John Bigsby, M.D., F.G.S. 4to. pp. 268. 

 London, 1868. Van Yoorst. 



IT is impossible to overestimate the value of exact books on any 

 subject, but especially does this apply to those which relate to 

 any branch of natural science. Such a work has just appeared from 

 the pen of another veteran in the ranks of geologists ; we say 

 another, because it is not many months since Sir Roderick Murchi- 

 son completed and issued the fourth edition of his ^' Siluria," ^ an 

 extended and more useful form of his original '^ Silurian System ; " 

 and another distinguished and equally laborious author, who has 

 grown grey in the service of geology and its sister science palgeon- 

 tology,^ has lately completed, in addition to other valuable works, his 

 seventh quarto volume of researches into the history of organic life 

 in the Lower Paleeozoic rocks of Bohemia.^ We need only mention 

 the name of Joachim Barrande to remind our readers of his splendid 

 work upon the Trilobites of the Silurian rocks of the Bohemian 

 basin,* and his even larger work upon the Cephalopoda of the 

 same area. Such works are lasting monuments of the learning, 

 labour, zeal, and research of their authors. If age and life-long 

 devotion to such labour be individually paralleled, and measured 

 by work done (or published) the new world may be proud of 

 James Hall and his voluminous palseontological researches into 

 the oldest forms of life, as exhibited upon the American con- 

 tinent.^ These men, and many others with the author of the 

 work before us, seem to have laboured in the same field of science 

 and research, but in very different regions of the globe. Murchison 

 over the oldest rocks of the western parts of England and Wales, 

 Scotland and Ireland, the Steppes and plains of Eussia and the 

 Ural mountains, etc., tracing, defining, and correlating the life- 

 groups and Rock-masses of these remote regions with those he had 

 determined and established in the British Islands. The other seems 

 to have lived to labour with determined purpose to work out in 



1 Siluria. Hist, of the older Rocks in the British Isles. 1867. 4th Edition. 



2 Barrande. 



3 Systeme Silurian du centre de la Boheme, Vols, for 1865-6-7-8 Cephalopoda 

 and Pteropoda. Par Joachim Barrande. 



* Systeme Silurian du centre de la Boheme, Vols. 1, 2, Crustaces Trilobites. Par 

 Joachim Barrande, 



Geological Survey of New York, Palaeontology. 6 Vols, quarto. 



VOL. v.— NO. LIII. 34 



