214 INSECTS. 



ment. He divided genuine insects into, 1. Those which after 

 leaving the egg appear under the form of the perfect insect, but 

 have no wings for some time afterwards ; 2. Those insects 

 which appear under the form of a larva, which, when full grown, 

 changes into a chrysalis, in which state it remains until its 

 parts are developed ; 3. Those which, having attained the pupa 

 state, do not divest themselves of their skin. The fourth divi- 

 sion of Swammerdam refers to animals of the classes Arach- 

 nides, Crustacea, and Myriapoda. In this idea he was followed 

 by Ray, whose Historia Insectorum, a posthumous work, was 

 published in 1710. In this work, which seems to have been 

 drawn up from the joint labours of Willughby and himself, Ray 

 divides insects into those which undergo no change of form, and 

 those which do undergo a change, and gives a detail of the va- 

 rious tribes belonging to the four kinds of metamorphosis esta- 

 blished by Swammerdam. About the same period the doc- 

 trine of equivocal generation was set at rest by the experiments 

 of Redi and Malpighi ; and the number of observers and writ- 

 ers in this branch of science went on increasing till the aera of 

 Linnaeus, whose powerful genius enabled him in this, as in other 

 branches of Natural History, to lay the foundation of arrange- 

 ments from which all that has since been done has emanated. 

 The characters upon which Linnaeus founded his arrangement 

 were chiefly the wings, and hence his system has been called 

 the alary system. The class Insecta of Linnaeus, however, as 

 it stands in the twelfth edition of his Sy sterna Naturce, includ- 

 ed the Crustacea and Arachnides. He divides the whole into 

 seven orders, viz. 



I. COLEOPTERA, (from xoAgos, a sheath, and irregbv, a wing.) 

 Wings four, the upper ones crustaceous, with a straight suture. 



IT. HEMIPTERA, (from 5j//,/*y, half, and mgbv.) Wings four, 

 semicrustaceous, incumbent. 



III. LEPIDOPTERA, (from XSTT/S, a scale, and crrggov.) Wings 

 covered with imbricated scales. 



IV. NEUROPTERA, (from i%oy, a chord or string, and vngbv.) 

 Wings membranous, with ribs or nerves ; anus unarmed. 



V. HVMENOPTERA, (from v/wv, a membrane, and fl 

 Wings membranous ; anus aculeate. 



