The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . ted into abroad and flattened square plate, having numerous transverseridges, serving for the purpose of bruising the leaves uponwhich these insects feed (fig. 9/). In some beetles also,which subsist upon the juices of flowers, or upon the flowingsap of wounded trees, &c., the jaws are of a membranousstructure, and quite unfitted for mastication. In the Hyme-noptera also, the jaws, although of the ordinary form, cannot,in many cases
The entomologist's text book : an introduction to the natural history, structure, physiology and classification of insects, including the Crustacea and Arachnida . ted into abroad and flattened square plate, having numerous transverseridges, serving for the purpose of bruising the leaves uponwhich these insects feed (fig. 9/). In some beetles also,which subsist upon the juices of flowers, or upon the flowingsap of wounded trees, &c., the jaws are of a membranousstructure, and quite unfitted for mastication. In the Hyme-noptera also, the jaws, although of the ordinary form, cannot,in many cases, be regarded as masticating organs, but ap-pear solely to be employed in the construction or the provi-sioning of the nest. In the Lepidoptera they are very mi-nute, membranous, and triangular, and placed on each sideof the labrum. In the Hemiptera they are very long, slen-der, and employed in conjunction \^dth the maxilla as lan-cets. They have also the same character in the Dipferajbut here they are often entirely wanting. They are, how-ever, particularly distinct in the gnats and gadflies {Tahanidceyfig. 88, m). 252 ptilota: imago—external anatomy. Fifjs. 99, Maxilla of the greatpirriis) seen from abo%c—from the back. water-beetle [Ht/droiis100, from below—lUl, Maxillce, or lower jaws {yax in the figures).—These organsare two in number, and are placed beneath the mandibles, from which they differin their less firm con-sistence and more com-plicated structure, be-ing formed of severalparts, and especially bythe possession of a slen-der articulated appen-dage or palpus, attach-ed to each. They ap-pear to be more espe-cially connected withthe lower lip, serving, in some instances, as a sheath for itsdefence; in the beetles, however, they are generally quitedetached. In a table of the comparative variation of thechief insect organs, Mr. MacLeay has shown that the maxillaeare less liable to vary than any other; hence it is importantto note the modifications to which they
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Keywords: ., bookau, bookcentury1800, booksubjectcrustacea, booksubjectinsects
