Entomology : with special reference to its biological and economic aspects . ich may possiblyhave been brought about simply by the backward pull of themuscles that move the head, has certain mechanical advantagesover the alternative condition, in securing, most economically,freedom of movement of the head and protection for the artic-ulation itself. The size and streng-th of the skull are usually proportionate ANATOMY AND PHYSIOLOGY 29 to the size and power of the mouth parts. In some insectsalmost the entire surface of the head is occupied by the eyes,as in Odonata (Fig-. 20, B) and Diptera (
Entomology : with special reference to its biological and economic aspects . ich may possiblyhave been brought about simply by the backward pull of themuscles that move the head, has certain mechanical advantagesover the alternative condition, in securing, most economically,freedom of movement of the head and protection for the artic-ulation itself. The size and streng-th of the skull are usually proportionate ANATOMY AND PHYSIOLOGY 29 to the size and power of the mouth parts. In some insectsalmost the entire surface of the head is occupied by the eyes,as in Odonata (Fig-. 20, B) and Diptera (Fig. 39). In mus-cid and many other dipterous larv?e, or maggots, the headis reduced to the merest rudiment. Though commonly more or less globose or ovate, the headpresents innumerable forms; it often bears unarticulated out-growths of various kinds, some of which are plainly adaptive,while others are apparently purposeless and often fantastic. Sclerites and Regions of the Skull.—The dorsal part ofthe skull (Fig. 33) consists almost entirely of the cpicraniinn, Fig.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
