. A manual of zoology. 242 MANUAL OF ZOOLOGY. consists of three segments, which are usually firmly united together. The abdomen contains from ten to eleven seg- ments. The appendages are also very constant in their arrange- ment throughout the Insecta, though variously modified in form in the different orders, ,3en' in accordance with differ- ences in mode of life. The head (Fig. 141) bears a pair of antennae, a pair of mandibles, and two pairs of maxillae. The antennae vary a good deal in size and shape in different insects. The mandibles (Fig. 142, md) lie at the Fig.
. A manual of zoology. 242 MANUAL OF ZOOLOGY. consists of three segments, which are usually firmly united together. The abdomen contains from ten to eleven seg- ments. The appendages are also very constant in their arrange- ment throughout the Insecta, though variously modified in form in the different orders, ,3en' in accordance with differ- ences in mode of life. The head (Fig. 141) bears a pair of antennae, a pair of mandibles, and two pairs of maxillae. The antennae vary a good deal in size and shape in different insects. The mandibles (Fig. 142, md) lie at the Fig. Lateral sides 0f tne mouth, in view of the head and its appendages. cerv, one of the cervical sclerites; ey front Qf which IS B. lTlOVa- eye; gen, gena; man, mandible; majc*, first pair of maxilla:; max*, second pair ]->le labrum Or Upper lip of maxilla; (labium). rr _ (Ibr). Each mandible is a single solid piece, and is devoid of palp. The second pair of maxillae (mx. 2) are united in their basal portions to form a lower lip (labium). Jointed palpi (pin) are borne both by the first pair of maxilla? (maxillary palpi) and by the second (labial palpi). All the jaws become differently modified in the different orders in accordance with differ- ences in the nature of the food. Insects, which like cock- roaches and beetles, masticate hard substances, have the mandibles strong and sharp and the maxillae well developed, and adapted to act as masticatory organs. Insects which, like cicadas, bugs, lice, and plant-lice, live on the juices of plants or animals, have the jaws in the form of sharp stylets, enclosed in a sheath or proboscis, for piercing the integu-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. N
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