4 MODERN CLASSIFICATION OF INSECTS. 



lice approaches very closely to that of such of the very few true 

 insects, which undergo an imperfect metamorphosis, without their 

 wings being developed ; as the bed bug, certain apterous Orthoptera, 

 &c. 



Dr. Hermann Burmeister has, however, introduced both the spring- 

 tailed insects and the lice amongst insects ; placing the suctorial lice 

 (Pediculidag) in the order Hemiptera, and the mandibulated lice (Nir- 

 midae) and the spring-tailed insects in an order with Libellula, Ephe- 

 mera, Termes, and Psocus. (Comp. his Handb. der Ent. vol. i. § 352., 

 and vol. ii. p. 39., and De Insect. Sijst. Nat. 1829.) He appears to 

 have been led to adopt this arrangement by giving too slight a weight 

 to the developement of organs of flight ; citing, in support of his 

 views, the occasional apterous conditions of certain true insects, and 

 even the occasional absence of wings in one of the sexes, as in the 

 glow-worm. In these instances, however, I can see but exceptions to 

 a general rule, for which allowances ought to be made, and, conse- 

 quently, as not warranting the introduction of entire groups of Apte- 

 rous animals into the class. 



It only remains for me to mention the system of Mr. MacLeay ; 

 which, from the philosophical manner in which the subject has been 

 ti'eated, merits particular notice. In this system, the metamorphotic 

 Annulosa are regarded as the true insects ; the classes Crustacea and 

 Arachnida are introduced, with the limits given to them by Latreille ; 

 but the four other groups, which have already occupied so much of 

 our attention, are, together with another group of Annulose animals, 

 formed into a separate class, under the name of Ametabola, " having- 

 no metamorphosis in the usual sense of the word, or only that kind 

 of it, the tendency of which is confined to an increase in the number of 

 feet." [Linn.Tr. xiv. p. 66.) All these Ametabola are destitute of wings, 

 but their respiratory system is similar to that of the true insects. It 

 would occupy too much space were I to recapitulate the arguments 

 adduced by Mr. MacLeay, as to the propriety of the establishment of 

 this class ; I must, therefore, refer the student to the fifth and sixth 

 chapters of the second volume of the Horcc Entomologicce, premising 

 only that I have adopted this classification, because it leaves the true 

 winged metamorphotic insects as distinct from the other groups, and 

 without expressing any opinion upon the Quinarian views of Mr. 

 MacLeay, or upon the introduction of the Vermes amongst the Ame- 

 tabola. 



