. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. i'il il 206 HIGH SCUOOL ZOOLOGY. namedâCaloplenus femur-rtihruni. Comparing it with tlio crayfish, wo find that thoro are conspicuous diffei-ences both as to the number and gi'ouping of the segments, and as to the number and nature of the appendages. Instead of a cephalo- thorax and abdomen, we find a liead composed of four segments (the number only to be arrived at from the a])pendages), a thorax consisting of three free segments (pro- meso- and meta- thorax), each of which bears a pair of walking legs,
. An introduction to zoology [microform] : for the use of high schools. Zoology; Zoologie. i'il il 206 HIGH SCUOOL ZOOLOGY. namedâCaloplenus femur-rtihruni. Comparing it with tlio crayfish, wo find that thoro are conspicuous diffei-ences both as to the number and gi'ouping of the segments, and as to the number and nature of the appendages. Instead of a cephalo- thorax and abdomen, we find a liead composed of four segments (the number only to be arrived at from the a])pendages), a thorax consisting of three free segments (pro- meso- and meta- thorax), each of which bears a pair of walking legs, and the two hindmost, each a pair of wings ; and finally, an abdomen of ten segments without obvious appendages (Fig. 139). 21. In the abdomen, theexoskeleton of each sogment is divi- sible into a sternum below, a tergnm abovoj and a lateral piece on each sideâthe pleurumâcoalesced with the tergum, and only indicated by the stigmata. In the meta- and meso- thorax (but not in the prothorax) a further differentiation is associated with the attachment; of the wings, for each tergum or notum is subdivided into an a,nterior scutum and a i>osterior scutellum, while the independent pleurum is subdivided on each side into an anterior epinierum and a posterior episternum. Only the sterna of the head-segments can be recognized, for the dorsal part of the exoskeleton of the head (ep^'^^anium) be- longs solely to the first segment. The thoracic legs are formed of the femur, tibia, and three-jointed " tarsus,"âthese names must not be supposed to indicate any homology with the parts so-called in Verte- bratesâarticulated to the thonix Ijy the "trochanter," "coxa" and "tro- Fig. 140.âMax!lla and labium of , . » r . i i , â , Caioptenus. (After Packard), c, chantme, Dut the head-appendages cardo; ; l,lacinia; e>i;<'^1ea; i« ^ i mi p', maxillary palp ;8m,8ubmentum; are moi"e COmpilcatea. Ihey Cm- rn, mentiim ; pf, palplfer;
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
