254 Notices of Boohs. [April, 



adduced. As the basis from which other inquirers will start 

 their labours, it will always be invaluable. The line of argument 

 pursued is throughout rigid and consistent; and if the conclusions 

 arrived at are ever shown to be erroneous, it will be not so much by- 

 discovering any flaw in Mr. Darwin's line of argument, as by a 

 substitution of other premisses for those on which he founds his 

 hypothesis ; in other words, by the discovery of some organic 

 law or laws governing the evolution of organic forms, of which 

 we are at present ignorant. 



Whether the dogma that Natural and Sexual Selection are of 

 themselves sufficient to account for the evolution of the lower 

 forms of animal life, and of man from those orders which are 

 most nearly allied to him, the progress of future research only 

 will show. 



General Outline of the Organisation of the Animal Kingdom, and 

 Manual of Comparative Anatomy. By Thomas Rymer 

 Jones, F.R.S. ; 4th Edition ; Illustrated by 571 Engravings. 

 London: Van Voorst, 1871. 



A Manual of Zoology for the Use of Students, with a General 

 Introduction on the Principles of Zoology. By Henry 

 Alleyne Nicholson, M.D., D.Sc, &c. Edinburgh and 

 London : Blackwood and Sons, 1870. 



Of the two books which we have here bracketed together, the 

 first is a new edition of a well-known and deservedly popular 

 text-book of Comparative Anatomy. Since the first edition of 

 the work was published, great advances have been made in the 

 study of zoology ; the improvements in the construction of 

 microscopes has much advanced our knowledge of the Infusoria ; 

 the researches of Van Beneden and Siebold have opened new 

 fields in the embryogeny of the Tceniadcc ; while the discovery by 

 Steenstrup of the alternation of generation of the Hydrozoa has 

 thrown a new light on many organic problems. More recently 

 the investigations of Huxley and others have necessitated, in the 

 present edition, a re-arrangement of the lower divisions of the 

 animal kingdom ; the separation of the Protozoa from the 

 ciliated Infusoria ; the abolition of the Radiata of Cuvier as an 

 independent sub-kingdom, and establishment of the Ccelenterata ; 

 and the transference of the classes Rotifera and Cirripedia into 

 close proximity with the Crustacea. For the general reader, as 

 well as the scientific student, Professor Jones's book is perhaps 

 the very best general hand-book for study or for reference ; and 

 for the benefit of those who do not already know it, we may 

 briefly indicate its general plan. Commencing at the bottohi of 

 the scale, the author takes each class in succession, and after a 

 general description of the class, describes in detail the anatomy 

 of some typical species, including, in the case of the higher 



