170 Louis Figuier. [April, 



pale sun struggling to, penetrate the dense atmosphere of the 

 primitive world, and yielding a dim and imperfect light to the first 

 created beings as they left the hand of the Creator, organisms often 

 rudimentary, but at other times sufficiently advanced to indicate a 

 progress towards more perfect creations." The absence of organisms 

 more advanced in the zoological scale than were the Trilobites, is no 

 proof that more highly organized animals did not exist on the 

 globe during the Cambro-Silurian period. Those who think the 

 Darwinian theory approximates to the truth, and especially those 

 who hold the " complete " theory, will of course believe that 

 animals classed as high among the Vertebrata as the Trilobites and 

 Cephalopoda of Lower Silurian rocks are among the Annulosa and 

 Mollusca, existed at that time in regions of the globe from which 

 the ocean, perhaps, for ever excludes the inquhing palaeontologist 

 from verifying his conjectures. The discovery of the Eozoon 

 Canadense in the Laurentian rocks, and the existence of beds of 

 limestone in the same system, seem to confirm the views of those 

 who regard the whole of the Sedimentary rocks, from the Silurian 

 and Cambrian upwards to the latest Tertiary beds, as including but 

 a partial and fragmentary record of the past life of the globe — 

 impressions of the last-formed links of the great chain of organic 

 life on our planet — a few of the last chapters in the book of 

 'Ancient Life.' 



Limestone is almost in every case, especially when found exist- 

 ing over extensive areas, the result of organic agency, having been 

 formed from the remains of marine animals, such as corals and 

 various molluscs. Limestone is never a deposit from solution except 

 in fresh water, and over very limited areas. Sea- water is computed 

 to contain much more carbonic acid than is necessary to keep the 

 lime existing in it in solution ; so that when we find a limestone in 

 a very ancient formation, although we may not be able to detect 

 any fossil remains, yet we may reasonably infer that it is the result 

 of organic agency. 



The author describes the character and geographical extent of 

 the rocks of the Cambrian, Silurian, and Old Ked Sandstone periods ; 

 and enumerates and describes the typical species of each formation. 

 He is particularly happy in his verbal pictures of those periods, as 

 well as in that of the succeeding Carboniferous era. The author's 

 efforts in this direction have been ably seconded by the artist, 

 whose pictures of the animal and vegetable life of each period are 

 admirably executed ; indeed all the plates in the book are splendid 

 specimens of wood-engraving, and are well printed, as will be seen 

 from the accompanying specimens, for which we are indebted to the 

 kindness of M. Figuier's English publishers. The student will 

 find the restorations of extinct animal and vegetable life of much 

 value, whilst the general reader will be no less instructed at 



