ENTOMOLOGY 661 he subdivides orthoptera into 3 orders, add- ing dermaptera (forficula) and dictyoptera, and introduces also omoptera and omaloptera. The classification of Kirby and Spence, as given in vol. iv. of the " Introduction to Entomology " (1815-'26), is as follows: I. Mandibulata, or insects with mandibles, containing the orders : 1, coleoptera; 2, strepsiptera ; 3, dermaptera; 4, orthoptera; 5, neuroptera; and 6, hyme- noptera. II. Haustellata, or insects with suc- torial mouths, containing the orders: 7, hemip- tera; 8, trichoptera; 9, lepidoptera ; 10, dip- tera; 11, aphaniptera; and 12, aptera (all wingless insects breathing through tracheae). It has been objected to this system that the 3d order is improperly separated from the 4th, and that the 8th forms naturally a part of the 5th. The system of Macleay is founded on the fol- lowing principles : 1, all natural groups return within themselves, and consequently present themselves in the form of circles ; 2, each of these circles contains five others, connected in the same way; 3, where the circles join, there are intermediate groups connecting them more closely ; 4, the members of each, at the points where the circles meet, exhibit analogies. The animal kingdom consists of five circles, one of which, the annulosa (crustacea and insects), consists of five principal groups, which may be represented as follows : The three orders of ametdbola, mandibulata, and haustellata only concern us here. Of the first, the myriapods join the crustacea, and the thysanoura and anoplura (parasita) join the mandibulata. The haustellata and mandibu- lata he calls insecta ptilota ; the former include lepidoptera, diptera, aptera (suctoria, Latr.), Jiemiptera, and homoptera; the latter include trichoptera, hymenoptera, coleoptera, orthop- tera, and neuroptera. These two circles are contiguous in the trichoptera and lepidoptera, the genus mystacides (Latr.) of the former making the transition to aglossa (Latr.) of the latter. Space will not permit the introduction of the families which he considers the connect- ing links between the orders of the two great divisions. This system, while it has many forced and unnatural affinities, presents much that is valuable in determining the groups of transition, which are found among insects as among other branches of the animal kingdom. His principal work, Horce Entomological, was published in 1819-'21. Burmeister divides in- sects, according to the completeness of their metamorphosis, into ametdbola and metdbola, each group presenting both haustellata and mandibulata, and subdivided according to the form of the larva, the structure of the wings, and the internal organization. His system is as follows : I. Insecta ametdbola, with imper- fect metamorphosis ; the larva, pupa, and per- fect insect resembling each other, the pupa eating and moving about : A. Having a sucto- rial mouth, with four fine setae enclosed in a sheath, and the palpi wanting, with order 1, Jie- miptera (bugs). B. With a masticating mouth : a, with four unequal wings, anterior ones leathery, the posterior membranous and folded longitudinally and once transversely ; protho- rax free, and many biliary vessels ; with order 2, orthoptera (locusts) ; 5, with four generally equal wings, never folded, with order 3, dicty- otoptera (cockroaches). II. Insecta metdbola, with perfect metamorphosis ; the larva a worm, of 13 segments, with or without legs ; the pupa motionless, or, if it moves, not eating. A. With suctorial mouth : a, with two naked transpa- rent wings, the posterior replaced by pedicu- lated knobs ; four biliary vessels ; larvae with- out feet; soft proboscis, with several setse and a pair of palpi ; prothorax not free ; with order 4, diptera (flies) ; 5, with four wings, gen- erally covered with scales, six biliary vessels ; larvae with feet and a distinct head ; the max- illae forming a spiral tongue; prothorax not free, but closely connected with the mesotho- rax ; with order 5, lepidoptera (butterflies and moths). B. With masticating mouth, or at least visible mandibles and palpi : a, with four equal- ly large or long wings, with reticulated ner- vures ; rarely more than eight biliary vessels ; prothorax always free; with order 6, neurop- tera (dragon flies) ; b, with four unequal wings, with variously branching nervures ; larvae gen- erally without head or feet, yet sometimes with both ; many biliary vessels ; prothorax not free ; with order 7, hymenoptera (bees, wasps) ; c, with four unequal wings, the anterior ones cor- neous ; larvae with head, with or without feet ; four or six biliary vessels ; prothorax always free ; with order 8, coleoptera (beetles). In al- most all these orders there are apterous fami- lies, genera, and species, whose place may be determined by their metamorphosis and the structure of the mouth ; but they never form a distinct order like the aptera of Latreille. Bur- meister maintains that all true insects undergo some metamorphosis, though in the apterous forms it may be difficult to detect it from the
