PREFACE TO THE SEVENTH EDITION. 



MORE important additions and alterations have been made 

 in the sixth and seventh editions than in any previous one. 

 The author has decided to consider the Hexapoda, Aruchnida, 

 and Myriopoda as sub-classes of Tracheata, and consequently 

 what have been in former editions regarded as sub-orders are 

 called orders. The Thysanura, moreover, are separated from 

 the Neuroptera, and regarded as a distinct order, comprising 

 synthetic types with features allying them to the Orthoptera, 

 Neuroptera, and Myriopoda. They are divided into two sub- 

 orders, the lower the Collembola of Lubbock ; and for the 

 higher sub-order, comprising the Lepismatidte and Campodeae, 

 the term Cinura (Hivfoo, to move; oupa, tail) is proposed. 

 The terms tenaculum and elater are adopted from the author's 

 previous writings for the " holder " and " spring " of the Col- 

 lembola ; and for the sucker or organ secreting the adhesive 

 material characteristic of the Collembola, the term collophore 

 is proposed. 



Brief mention has been made of the Pycnogonidse, which 

 are placed among the mites ; also of the Peripatidea, which 

 are given a place next to the sucking Myriopoda, since they 

 have been proved by the researches of Mr. Moseley to be 

 Tracheata. 



On page 240 the discovery by Mr. Swinton of an auditory 

 apparatus at the base of the abdomen of Lepidoptera has 

 been noticed, as well as Mr. Mason-Wood's discovery that 

 Mygale and Scorpio stridulate (page 628). A number of minor 

 changes and corrections have been made in the plates. 



Some important changes have been made in the classifica- 

 tion of the Coleoptera which do not appear in the text. The 

 weevils, Curoulionidce, should, in accordance with the views 

 expressed by Dr. Le Conte, be placed at the end of the group. 

 The Coccinellidce and Erotylidw should also, in accordance 

 with the views of Mr. G. R. Crotch (Check-List of the 



