NOTICES OF NEW BOOKS. 77 



prove his thesis, Mr. Moore had to disprove this theory before 

 offering his own explanation of the facts. His investigation of 

 the geological characters of Central Africa goes to prove that there 

 is no foundation for the Murchison hypothesis, and that there is 

 evidence of vast disturbance in the region of the great lakes. 

 Mr. Moore's conclusion is that Tanganyika was originally stocked 

 with halolimnic animals * from a western sea, of which the great 

 lake itself, and the vast back waters of the Congo, may be said to 

 be the last remains. Owing to geological changes these became 

 a more and more land-locked sea, " and in the course of time the 

 water in these areas became freshened, and consequently a large 

 section of the old marine fauna died out, while those fishes which 

 could withstand the change migrated to a certain extent through- 

 out the fresh waters of the continent." The reader is not simply 

 asked to accept this proposition, but is afforded a long zoological 

 argument, based on well-marshalled facts, which makes a con- 

 trary opinion almost impossible. 



We wish space would allow mention of many incidental facts 

 and observations recorded in this volume : such as the opinion 

 as to the origin of park-lands, which the writer of this notice has 

 often seen and pondered in the Transvaal ; that floral changes in 

 these areas are due to physical conditions, and not to the struggle 

 for existence among different species ; and that in many of the 

 great lakes " there is hardly so much variety of life as there is 

 in an ordinary American or European puddle." The recently 

 discovered fishes of Lake Tanganyika, which consist of eighty- 

 seven species, of which seventy-four have been described as new, 

 are enumerated with Mr. Boulenger's original descriptions, 

 accompanied by a reproduction of Mr. Green's excellent drawings 

 of the same. The Molluscs, Gastropods, Crustacea, Medusse, 

 Sponges, Protozoa, and new Polyzoan receive ample treatment ; 

 while the whole work is so lavishly illustrated as to render it a 

 notable addition to our knowledge of African zoology. 



* " Organisms possessing definitely marine and somewhat archaic cha- 

 racters." 



