. The animans and man; an elementary textbook of zoology and human physiology. s or boards,on damp soil, etc. They run aboutquickly, and feed chiefly on decayingvegetable matter. They are night-scavengers. Although commonly calledbugs and supposed to be insects,they really belong to the Crustacea,that class of animals which includesFIG. 63. A damp-bug, the crayfish, lobster, and crabs. Ex-Isopod. (Four times amine the body of a dead pill-bug. It is oval and convex above, rather pur-plish or grayish brown, and smooth. Note its division intohead, thorax, and abdomen. Find the eyes, the antennae,
. The animans and man; an elementary textbook of zoology and human physiology. s or boards,on damp soil, etc. They run aboutquickly, and feed chiefly on decayingvegetable matter. They are night-scavengers. Although commonly calledbugs and supposed to be insects,they really belong to the Crustacea,that class of animals which includesFIG. 63. A damp-bug, the crayfish, lobster, and crabs. Ex-Isopod. (Four times amine the body of a dead pill-bug. It is oval and convex above, rather pur-plish or grayish brown, and smooth. Note its division intohead, thorax, and abdomen. Find the eyes, the antennae, andthe mouth-parts. All the locomotory appendages are adaptedfor walking or running, not swimming. How many pairsof legs are there? Find gills and gill covers. Although thepill-bugs do not live in the water they breathe partly atleast by means of gills (though they may breathe partlythrough the skin). It is therefore necessary for them tolive in a damp atmosphere, so that the gill membranesmay be kept damp. If these are not moist, they will notpermit the exchange of ARTHROPODS AND MOLLUSCS 155 Millipeds and centipeds (class Myriapoda).—The Myria-poda are land-animals breathing by means of trachea?like the insects. In them the body-segments are nearlyuniform in character with the exception of the head, which,as in the insects, bears the mouth-parts and antennae. Thereis no grouping of the body-segments into regions except as the head is distinct from the rest of the body. (In a few myriapods there are indications of a division of the hind body into thorax and abdomen.) The presence of true legs on all the
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Keywords: ., bookcentury1900, bookd, booksubjectphysiology, booksubjectzoology
