14 
BRITISH BEETLES. 
aberrant members of the order Insecta, even if they 
can be included within it at all, and need not be further 
noticed. 
There only remain the Achreioptera, containing 
Platypsylla (a parasite on the beaver) and the Strep- 
sip ter a (parasitic on bees, of which the best-known 
member is Stijlops) ; these, however, are now usually 
regarded as abnormal members of the Coleoptera, and 
as representatives of the latter occur in Britain, they 
will again be noticed in due course. 
The foregoing system of classification of the Insecta 
will be found quite sufficient for all practical purposes, 
but a more intricate and more scientifically correct 
arrangement is proposed by Brauer (Systematisch. 
Zool. Studieu, S.B., Akad. Wien., xci., Abtli. i. 1885; 
vide Rolleston’s “ Forms of Animal Life,” 2nd edition, 
pp. 509 — 511) ; it is based on recent advances in 
anatomy and physiology which it would take a great deal 
too much space to discuss in a work like the present ; 
in this classification the Collembola and Thysanura are 
separated off as a primitive group of the Insecta, in 
which the wings have never been developed, and the 
remainder are divided into sixteen classes or characters 
depending chiefly on the formation of the mouth parts, 
the anatomy of the genital organs, and the complete- 
ness or incompleteness of the transformations, all taken 
together, instead of a predominant importance being 
given to one particular character, as has too often been 
the case in the older systems ; these sixteen divisions 
are as follows : — 1. Dermaptera (Earwigs) ; 2. Ephe- 
meridas (May Flies ) ; 8. Odonata ( Dragon Flies) ; 
4. Plecoptera = ( Perlaricc or Orthoptera Amphibia 
(Stone Flies) ) ; 5. Orthoptera (Cockroaches, Leaf In- 
