The Journal of microscopy and natural science . ed with muscles of a wing-like shape, which are known as the alary muscles and whichgovern the pulsations. The chambers are furnished with valvesand arteries for the exit of blood, and slits known as ostia for thereturn of blood to the heart. The remaining chapters of the book treat of the followingOrders of Insects, viz. :—Aptera, Orthoptera, Neuroptera,and a portion of Hymenoptera, Insects form by far the larger part of the land animals of theworld. They outnumber in species all the other terrestrial ani-mals together, while, compared with the
The Journal of microscopy and natural science . ed with muscles of a wing-like shape, which are known as the alary muscles and whichgovern the pulsations. The chambers are furnished with valvesand arteries for the exit of blood, and slits known as ostia for thereturn of blood to the heart. The remaining chapters of the book treat of the followingOrders of Insects, viz. :—Aptera, Orthoptera, Neuroptera,and a portion of Hymenoptera, Insects form by far the larger part of the land animals of theworld. They outnumber in species all the other terrestrial ani-mals together, while, compared with the Vertebrates, their numbersare simply enormous. Yet they attract but little attention from PERIPATUS, MYRIAPODS, AND INSECTS. 181 the ordinary observer, this being probably primarily due to thesmall size of the individual Insect, which leads the unreflecting totreat the creature as of little importance. . The largestInsects scarcely exceed in bulk a mouse or a wren, while thesmallest are almost or quite imperceptible to the naked eye, and. Fig. II. Lithobius dissected(after Vogt and Yung). a, Antennse; b, Poison-claws ; c, Brain ; d, Salivary glands ; e, Legs ; /, Nerve cord ; g, Malpighian tube ; h, Malpighian tube ; i, Vesicula seminalis ; /, Accessory gland ; k. Accessory gland; /, Testis ; ;«, Thigh-gland ; «, Digestive tube. yet the larger part of the animal matter existing on the lands ofthe globe is in all probability locked up in the form of as a whole, they are the most successful of all the forms ofterrestrial animals. 182 PERIPATUS, MYRIAPODS, AND INSECTS. The series of rings of which the external crust or skeleton ofInsects is composed exhibits great modifications, not only in thevarious kinds of Insects, but even in the different parts of thesame individual, and at successive periods of its development. Many of the anatomical structures have positions in the bodythat are fairly constant throughout the class. Parts of the respira-tory and muscular s
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