Cooke : On the Cla?stficatio]S" of Insects. 



67 



Monograph of the Collembola and Thysanura," does not seem to 

 regard them as belonging strictly to the class Insecta, though nearer 

 to this class than they are to the Crustacea or Arachnida. According 

 to Stephens the order Aptera consists of the two families Pediculidae 

 and N'irmidse. Now it is possible that the Pediculidae, or at least the 

 greater portion of them, will have to be associated with the Hemiptera. 

 Of the Nirmid83, most of which are called bird-lice, I will not express 

 an opinion, except that they ought not to form a distinct order of 

 insects. 



Eestricting, then, the class Insecta as it has been done by Westwood 

 and by Newman, and carrying out the metamorphotic system of 

 arrangement, the class will be separable first of all, into two divisions, 

 which may be characterised thus : 



Division I. Division II. 



Pupa unable to feed. Pupa able to feed. 



. In the second division the pupa is as active and voracious as the 

 larva, and in some cases more so. In the first division there is much 

 difference in the power of motion possessed by the pupa, and this is 

 most evident among the Diptera ; in a large proportion of this order 

 the pupa is wholly incapable of any motion : whilst of those which 

 live in the water up to the time of their assuming the perfect state, 

 the pupce of some families possess considerable power of motion. 



I will now proceed to state my views as to the number of orders in 

 the class Insecta, and as to their arrangement on the principle of 

 commencing with the highest development. The following table 

 exhibits six orders in the first division, and six orders in the second, 

 viz : — 



Dn^isioN I. 



1. Coleoptera 



2. Hymenoptera 



3. Diptera 



4. Lepidoptera 



5. Trichoptera (caddis-flies) 



6. Stegoptera (Newman in part 



= Neuroptera planipennia 



Division IL 



1. Neuroptera odonata (Dra- 



gon-flies only) 



2. Neuroptera Hetera 



3. Orthoptera 



4. Hemiptera. 



5. Homoptera 



6. Thysanoptera (Haliday) 



1. Coleoptera. — In the year 1861 Waterhouse published a " Cata- 

 logue of British Coleoptera," in three forms, one of which was intended 

 for labelling cabinets — a most valuable boon to collectors and students 

 of this order at that time. The arrangement was purely a tarsal one. 

 After ten years, when the number of British species had considerably 



