INSECT A, 



375 



/ the mentum, i the labium, k the labial palp, * the lingua or ligula^ 

 ** the paraglosscB. This definition and nomenclature of the bee's 

 trophi are indispensable for conveying the results of such comparisons 

 as those which enabled the venerable Kirby to enrich Entomology 

 with so valuable an accession of knowledge as is contained in his 

 " Monographia Apum Angliag," a work which the young Entomolo- 

 gist may take as a model. 



In the Hemiptera both the mandibulee and maxillas are alike 

 attenuated, and prolonged into stiff needle- or lancet-shaped organs, 

 which are protected by a sheath formed by the equally elongated 

 labium, the upper groove of which at the same time serves to conduct 

 the liquid food into the mouth : the maxillary and labial palpi have 

 disappeared ; the latter may have coalesced with, and transferred 

 their properties to, the labial sheath. With such an instrument 

 the Cicada perforates the bark of the trees on which it lives, and 

 exhausts their sap ; and with a similar modification of the trophi, the 

 bug and flea pierce the skin and suck the juices of animals. 



In the blood-thirsty Diptera, as the gnat and forest fly, the labrum, 

 as well as the two lateral pairs of jaws, are prolonged into lancet- 

 shaped organs, and are sheathed in a thickened lower lip, which is 

 terminated by two fleshy suckers : the maxillary palpi are attached 

 to the base of the maxillae. 



The singular spiral "antlia" of the butterfly and other Lepido- 

 ptera is formed by the elongated slender maxillae, still characterised 

 by the minute palpi at their base. The inner margins of the max- 

 illae are concave, and the edges of the channels are in close contact, 

 or are confluent, so as to form a canal along which the juices of 

 flowers can be pumped up into the mouth. Each maxilla is likewise 

 hollow, and it is uncoiled or coiled by the varying tension of this 

 canal. The labial palpi are of large size, and defend the antlia when 

 it is retracted and coiled up. The labrum is a small triangular 

 piece, which bends down towards the mouth, and the rudimental, 

 conical, slightly bent mandibles are hidden by the labial palpi. 



The large curved piercing jaws of the Centipede are hollow, and 

 traversed by the duct of a poison-gland. The anterior pair of legs 

 are modified to come in aid of the jaws in some predatory insects, 

 notably in the Mantis, Nepa, and Ranatra, where they serve to 

 seize and hold the food to the mouth. 



The alimentary canal is most simple in the larvae of insects, in 

 which, as in worms, it usually extends, without convolutions, from 

 one end of the body to the other ; in a few larvae, as that of the bee, 

 it has only the anterior opening or mouth, and the opposite or anal 

 orifice is not developed until the pupa-state. In all mature insects 



B B 4 



