Bibliographical Notices. 55 



The general nature of his lectures may be inferred from the work 

 before us, and Dr. MantcU carefully revised every edition. The pre- 

 sent or seventh edition is, however, considerably improved and aug- 

 mented, and evinces much pains-taking and research, — the editor 

 having spared no time or labour in working up the discoveries 

 accumulated during the ten years that have elapsed since the pre- 

 vious publication, and which have been concisely but carefully incor- 

 porated in the present volumes. In fact, not only has much new 

 matter been added, but many portions re-written and so far modified 

 as to bring the work up to the present state of the science, and make 

 it an exposition of the j)hilosophy of geology. Copious notes are 

 inserted, and numerous useful references given, so as to enable the 

 reader to refer to any subject in a more detailed manner. 



The original form of the work is retained — the division into eight 

 lectures, — some of these, from their length, being again divided, and 

 the subjects treated successively from the newer to the older depo- 

 sits. The additional matter generally incorporated in each chapter 

 contains all the more important and useful points of the science. In 

 the Tertiary strata, the labours of Ed. Forbes and Prestwich as im- 

 proving the classification of these rocks are fully given, more espe- 

 cially m the Isle of Wight district, and the foreign equivalents pointed 

 out. Considerable improvements are effected in the part treating of 

 the Cretaceous rocks, both as regards the fossils and the foreign range 

 of these deposits. A. concise acc-ount is given of the Foramiuifera 

 and Bryozoa, the editor giving his reasons for retaining the latter term 

 instead of Polyzoa, used by some naturalists (p. 600). The import- 

 ance of the Foramiuifera in a geological point of view must not be 

 underrated, independently of their remarkable forms and structure, 

 as well as their endless varieties, which have exercised the skill and 

 excited the admiration of collector and author. For mucii critical 

 research on the numerous recent and fossil Microzoa we are indebted 

 to the labours of Dr. Carpenter, Messrs. Williamson, Jones, and 

 W. K. Parker. 



The favourite subject of Dr. Mantell, the Wealden, is considerably 

 improved, modified, and enlarged, the new facts connected with the 

 Purbeck strata, arising from the researches of Ed. Forbes, Austen, 

 and Fisher, being fully given. Much yet remains to be effected 

 respecting the Wealden proper, both as regards the relative position 

 of the strata composing it (we allude especially to the Asburnham 

 beds) and also as to the physical geography of that period, whether 

 fluviatile or estuarine, whether the result of the action of one river or 

 many rivers and small streams emptying themselves into an adjacent 

 estuary, and their general direction, — a subject upon which the 

 researches of Mr. Fisher and Mr. Godwin-Au^sten have thrown con- 

 siderable hght. Nor should we forget the labours of Messrs. Beckles 

 and Brodie, whose discoveries have added so much to the peculiar 

 mammalian fauna of this period. 



In relation to the history of the Wealden, with which the name of 

 Dr. Mantell must always be intimately associated, we cannot, how- 

 ever, forbear to notice the researches of Dr. Fittou connected with 



