BOOK NOTICES 



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the stomodoeum and proctodEeum are epiblastic invaginations, while 

 the mesenteron is hypoblastic — the extraordinary extent of the epiblast 

 infolding, orally and aborally, not being sufficiently conveyed by the 

 words ' the mesenteron of the Cockroach is very short.' The con- 

 dition in these Arthropods is indeed precisely the reverse of that in 

 higher forms — the epiblast invagination being in Vertebrates reduced 

 to its smallest limits, while almost the entire length of the alimentary 

 tract is lined by hypoblast. The diagrammatic figures of the mouth- 

 parts in various insects, as well as Mr. Newton's well-known figures, 

 will be of great utility to the student ; indeed, the illustrations, as a 

 whole, are clear, bold, and well executed, and merit the highest 

 praise. It is, of course, impossible to refer to the various parts of 

 the book seriatim, and we must pass over the opening chapters 

 treating of the classical researches of Malpighi, Sw^ammerdam, and 

 other pioneers in insect anatomy, the zoological position of the 

 Cockroach, and the chapter on its food, habits, &c., which contains 

 many interesting facts. The account of the exoskeleton is, perhaps, 

 the best chapter, as it is also the longest, and anyone who will turn 

 these pages to practical account by examining — book in hand— the 

 Cockroach itself, and following systematically the account given, will 

 accomplish a task in Insect Morphology as thorough and complete 

 as it will be pleasurable. We notice that while the dorsal and ventral 

 divisions of the thoracic segments are named, the usual designations 

 of the segments themselves — viz., pro-, meso-, and meta-thorax — are 

 omitted, although the last name does occur on p. 62. Chapters V 

 and VI treat very fully of the muscles and nerves — the histological 

 figures being noteworthy — while the curious facts brought together 

 under the heading ' Muscular Force of Insects ' will interest many for 

 whom much of the book will be unattractive detail. Chapter VIII, 

 on Circulation and Respiration, is also a good piece of work, and it 

 includes a brief account of respiratory movements by Prof. Plateau, of 

 Ghent. Reproduction and Development occupy two chapters which 

 should have been amongst the most valuable and interesting in the 

 book; but they are somewhat disappointing, and Mr. Nusbaum's brief 

 account of the formation of the embryonic layers, &c., is less full 

 and satisfactory than we could have wished, while the section on 

 Animal Metamorphoses calls for revision. The chapter on the 

 Genealogy of Insects is far too brief for so profound a topic, 

 and does not sufficiently exhibit the importance of those features 

 in Peripatus^ which point not merely to an ancestral kinship of 

 Tracheates and Annelids, but are leading some zoologists to favour 

 the inclusion of Arthropods and Annelids in one large group of 

 metamerically segmented animals, the Arthropoda being more nearly 



Feb. 1887. 



