PREFACE TO THE SIXTH EDITION. 



MOKE important additions and alterations have been made 

 in this edition than in any previous one. The author has de- 

 cided to consider the Ilexapoda, Arachnida, 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 Lepismatidae and Campodea>, the term <'!inn-n 

 (nivlcj, to move; ovpa, tail) is proposed. The terms tena^n- 

 lion and elttter are adopted from the author's previous writ- 

 ings for the "holder" and "spring" of the Collembola; and 

 for the sucker or organ secreting the adhesive material char- 

 acteristic of the Collembola, the term collophore is proposed. 



Brief mention has been made of the Pycnogonidae, 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, Curculionidce, should, in accordance with the views 

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

 The Coceinettidce and Erotylidoe, should also, in accordance 

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



