Kirby and Spence's Introduction to Entomology/. 125 



Letters into which it is divided would require an article more 

 extended than the present, and the whole of one of our numbers 

 would scarcely suffice to convey an adequate outline of the vast 

 mass of important information embodied in these volumes. Our 

 notice must therefore be limited almost to a mere enumeration of 

 some of those striking points by which the attention of the scien- 

 tific reader will be most forcibly arrested. The remainder we 

 must, though reluctantly, pass by, with the single observation 

 that there are few pages of the work from which Entomologists, 

 even of the highest order, will not derive at once information and 

 amusement. 



Of the contents of the first two volumes of the Introduction 

 to Entomology it is unnecessary for us to speak, as they are 

 doubtless well known to every one of our readers. In the pre- 

 sent volumes, which complete the work, the subjects are thus 

 arranged: definition of the term insects; states of insects; their 

 external anatomy ; their internal anatomy and physiology ; their 

 diseases ; their senses ; Orismology, or explanation of the terms 

 employed in Entomology ; systems ; history of the science ; geo- 

 graphical distribution of insects; methods of collecting and pre- 

 serving them ; and the mode to be pursued in their investigation. 



On the first of these subjects, the definition of the term Insect, 

 Messrs. Kirby and Spence differ from all previous systematists, 

 the characters employed by them being designed to embrace all 

 those annulose animals in which respiration is performed by means 

 of tracheae. Their Insecta consequently correspond with the 

 Insectn and the Tracheau Arachnida of Latreille and Lamarck • 

 with the Insecta., Acari^ and Myriapoda of Dr. Leach ; and with 

 the Mandibulata, Ilatisfellaia, many of the Arachnida, and nearly 

 the whole of the Ametabola of Mr. W. MacLeay. The only an- 

 nulose animals excluded are the ylrachnida, distinguished by hav- 

 ing sacs for respiration, and the Crustacea, in which that office 

 is performed by gills. The function thus relied on for their 

 chief distinction is one of undoubtedly primary importance, and 

 the division deduced from it is shown to be strongly supported by 

 the differences observable also in the systems of circulation, di- 

 gestion, and generation. The relation borne by insects to other 



