Bibliographical Notices. 75 



principles and facts of the vast and ever-increasing science of 

 Palaeontology. 



The work is divided into three parts : the first part contains a 

 general introduction to the study of palaeontology, and treats of the 

 characters, formation, and succession of the aqueous rocks, geolo- 

 gical continuity and contemporaneous deposits, the conclusions to 

 be drawn from fossils, the respective value of the vertebrates, inver- 

 tebrates, and plants as tests of geological age and position of strata, 

 and the general succession and progression of organic types, with a 

 tabular arrangement of the leading subdivisions of the animal king - 

 dom. Some additional matter is distributed in the six chapters 

 forming this part, as regards fossilization, the condition and mode of 

 occurrence of fossils (which might have been extended), the re- 

 placement of organic and other substances by silica and carbonate 

 of lime. The chemical and organic origin of flint and limestones is 

 fairly explained, as also that of phosphate of lime, either dissemi- 

 nated or concretionary in the sedimentary rocks due to organic 

 agency ; but this does not account for the veins of apatite or phos- 

 phorite in Spain, Norway, and other places ; and it may be doubted 

 how far the thick deposits of apatite in the Laurentian of Canada are 

 directly due to vital agency. The origin of the red clay of the 

 Atlantic depths (p. 25) has been attributed to other sources than 

 the disintegration of the tests of Foraminifera. The " colonies " of 

 Barrande (p. 53), like those stated to occur in the Lake district, 

 may perhaps be otherwise interpreted than by the explanation 

 given (p. 5-4), when the contained fossils or the physical structure 

 of the district is further investigated. 



The second part, comprising the history of the Invertebrata and 

 Vertebrata, forms by far the larger part of the two volumes 

 (chaps, vii. to xlviii.) ; and of these two divisions the former natu- 

 rally occupy the greater space, on account of their state of preserva- 

 tion, their comparative abundance and general distribution in the 

 sedimentary strata, and " especially upon the ground that palaeon- 

 tological students are, as a rule, much more largely interested with 

 the former than the latter." 



The six subkingdoms of the Invertebrata are treated in a somewhat 

 similar manner, although not upon any absolutely uniform plan, as to 

 the general diagnostic characters and the characters of their respec- 

 tive classes and orders, their distribution or range in time, and to 

 the part which any of them has notably contributed to the forma- 

 tion of the solid crust of the earth. A short summary is generally 

 given of the principal fossil groups, the object being to select " for 

 notice and characterization those leading types of each great group 

 of fossils which may seem to demand mention on the ground of their 

 being common, or in other respects, geologically or zoologically, of 

 peculiar importance." 



This object is carried out in the successive chapters. The Brachio- 

 poda, from their importance, are fully noticed, as also the Lamelli- 

 branchiata ; the characters of the chief groups and genera and their 

 geological range are also given. In noticing the peculiar mode of 



