The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . composed of anumber of sclerites firmly sutured together, so that the primitivesegmentation is masked. Above is the crown (vertex or epicranium),on which or on the front may be seated three simple eyes (ocelli).Below this comes the front, and then the face or clypeus, to which avery distinct upper lip (/aiir«m) Is usually jointed. Behind thelabrumarises a process—the epipharynx—which in some blood-suckinginsects becomes a formioable piercing-organ. On either side avariable amount of convex area is
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . composed of anumber of sclerites firmly sutured together, so that the primitivesegmentation is masked. Above is the crown (vertex or epicranium),on which or on the front may be seated three simple eyes (ocelli).Below this comes the front, and then the face or clypeus, to which avery distinct upper lip (/aiir«m) Is usually jointed. Behind thelabrumarises a process—the epipharynx—which in some blood-suckinginsects becomes a formioable piercing-organ. On either side avariable amount of convex area is occupied by the compound eye;in many insects of acute sense and accurate flight these eyes are verylarge and sub-globular, almost meeting on the middle line of the CHARACTERS] HEXAPODA 419 head. - Below each eye is a cheek area (^ena), often divided into ananterior and a posterior part, while a distinct chin-sclcrite {gula) isoften developed behind the mouth. Feelers.—Most conspicuous amonR the appendnRCs of the head arethe feelers or antennae, which correspond to the anterior feelers. Fioni Miall and Denny, The Cochraack, Lovdl Reeve & Co. FiC. I.—Head and Jaws of Cockroach (Blatta). Magnified 10 times. A, Front; B, side;Cback; v, vertex; /, frons; ct, clypeus; Ibr, labrum; oc, compound eye; ge, gcna; mn,mandible; ca, si, pa, ga, la, cardo, stipes, palp, galea, lacinia of first maxilla; sm,m, pa,pg,submentum, mentum, palp, galea of 2nd maxilla. (antennules) of Crustacea. In their simpler condition they are long and many-jointed, the segments bearing numerous olfactory and tactile nerve-endings. Elaboration in the form of the feelers, often a secondary sexual character in male insects, may result from a distal broadening of the segments, so that the appendage becomes serrate, or from the development of processes bearing sensory organs, so that the structure is pinnate or feather-like. On the other hand, the number of segments may be reduced, certain of them often bec
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
