DISTRIBUTION OF INSECTS INTO ORDEKS. 21 



founded upon the structure of the organs of flight, of which Linnai-us 

 was the founder, and by whom insects were thus classed in accordance 

 with the gradual diminution in the number and consistency of their 

 wings. 



m, ^ • f horny, with a straight suture - - 1. Coleoptera. 



I ne anterior -s 



|_semicrustaceous, incumbent - - 2. Hemiptera. 



r covered with scales - - - 3. Lepidoptera. 



Wings. -{ All < , , J fimarmed - - 4. Neuroptera. 



I membranous, abdomen < ... . - tt . 



(_ [_ with a sting - o. Hymenoptera. 



2 With a pair of halteres in the place of the posterior pair 6. Diptera. 



.0 i.e. Destitute of wings and elytra - - - 7. Aptera. 



The celebrated Swedish naturalist, De Geer, proposed another 

 distribution of insects in 1778, the primary anol secondary divisions 

 of which were formed for the most jiart upon the structure of the 

 wings, which were also employed to characterise the orders. The 

 structure of the mouth was, however, regarded as a secondary 

 character of the latter ; the consequence of which was the neces- 

 sary and advantageous separation of the Caddice-flies and Ephemerae 

 from the other Neuroptera, under the name of Elinguia*; and the 

 division of the Linnaean Hemiptera into three orders — Siphonata * 

 (Cicada, &c.), ajjd Dermaptera*, having a suctorial mouth (Cimex and 

 Nepa), and Hemiptera* having a mandibulated mouth, (Mantis, 

 Gryllus, Blatta, and Forficula.) The genera Coccus and Pulex were 

 also respectively raised to the rank of distinct orders. The genera 

 Termes and Psocus, together with the spring-tailed insects and lice, 

 formed another order of the remainder of the Linnaean Aptera, which 

 were divided into two others, thus forming fourteen distinct orders. 



This was a great step made in the distribution of insects ; and the 

 partial success with which the employment of the variation of the 

 mouth was attended, probably induced Fabricius to construct his 

 Cibarian system, founded upon the characters of the Trophi alone. 

 This w^as as follows : — 



* Mandibulated Insects. 



A. Tico pairs of jaivs. 

 a. The lowei'pair Palpigerous. 

 1. Eleutherata (Coleoptera Z., Beetles.) Maxillae naked, free. 



* These names were proposed by lletzius, the commentator of De Geer (Gen. et 

 Spec. Ins. Lips. 1783. ) That of Dermaptera has, by some accident, been misapplied 

 by English entomologists for the Earwig, instead of the Cimicida^, for which it 

 was proposed. 



c 3 



