316 Biliographical Notice. 



kept in view ; and the author looks at the relationship of creatures to 

 conditions from a teleological point of view. The evolutionist, how- 

 ever, will find little to interfere with the feasibility of his scheme, 

 except the indistinctness of the earliest and of many of the inter- 

 mediate circumstances of the life-historj- of a species. The natu- 

 ralist, whatever views he may adopt, will here find much that is 

 worth noting, and not attainable without such patient and work- 

 loving research as has produced the ' Thesaunis Siluricus ' and its 

 Introduction. Other matters for consideration are suggested at 

 p. li, such as a comparison of Silurian and Recent Sea-beds, the 

 Bathometry of ancient and modern molluscan life, the possible syn- 

 chronism (or, rather, homotaxis) of strata, the foreshadowing of 

 coming faunal groups, and so on. 



AYith reference more especially to the first six lines of consideration 

 above noted, the author has treated of some great groups of Silurian 

 animals, namely, the Gasteropoda,. Tiilobita, Cephalopoda, Brachio- 

 poda, and Echinodermata (pp. vii-xx), showing, in his concise and 

 almost quaint, apothegmatic style, the results of a rigid examination of 

 the multitudinous entries in the ' Thesaurus,' and in numerous tables 

 of condensed information their localization, distribution, habitats, 

 appearances, reciirrency, and other conditions and peculiarities. At 

 p. XX he treats of the flora and fauna of the so-called " Primordial" 

 stage of Silurian life ; at pj). xxiii-xxxii he gives a very valuable 

 series of observations on the Silurian fossils of Bohemia, which, by 

 their local abundance and the scientific care with which they have 

 been discriminatingly collected and described, are of as great a value 

 as the perfect dredgings of any sea-area ; and, indeed, they are 

 more complete. Their relationships both among themselves and to 

 other Silurian groups can now be easily mastered ; and geologists 

 vnll thank both Dr. Bigsby, for his analytical work, and the eminent 

 Barrande, for the liberal communication of facts the harvest of years 

 of labour, and of ripe opinions due to careful judgment and extensive 

 knowledge. The long special lists of M. Barrande's latest additions 

 to Bohemian paloeontology, given on several pages in the 'Addenda' 

 to the ' Thesaurus,' are proofs of the anxious care to complete a good 

 work, and of the ready aid given in furtherance thereof. 



The universality of the Silurian system of rocks (p. xxxiii) is the 

 only other subject that the author has allowed himself to treat of, 

 and that briefly. " More than fifty great terrestrial spaces, scattered 

 over the whole earth, are oecxipicd mth some portion of the Silurian 

 succession of rocks, with their proper stratigraphical habitudes, 

 coimexions, itc." "Well may Dr. Bigsby wish to see the life-con- 

 ditio7is of this great old ocean -territory brouglit before the mind, as 

 a grand picture of creative power, skill, and goodness ! He has 

 commenced the sketch of this scene of restored existences ; he has 

 Btretched the canvas, prepared the palette, and sketched in the out- 

 lines of the work ; he has copied his lines and taken his tints from 

 many other studies and palettes besides his own, in good faith, with 

 perfect confidence in the ready cooperation of geologist and natu- 

 ralist, and in strong hope that the finished work will be a labour of 



