. An introduction to zoology : for the use of high schools . HIGH SCHOOL ZOOLOGY. 203 are the most important. Both have the two pairs of mouth-appendages and the four pairs of walking legs, but the form ofthe body is very different in the two groups, on account ofthe separation of the abdomen in the spiders pi-oper, by aslender stalk, and the presence at its extremity of the spin-nerets (Fig. 137). Some of the chief structural peculiarities of the spidersmay be gathered from Fig. 138. The two-jointed cheliceriBterminate in a powerful claw, perforated by the duct of a. I Fig. 13S.—^Diayramiiiat
. An introduction to zoology : for the use of high schools . HIGH SCHOOL ZOOLOGY. 203 are the most important. Both have the two pairs of mouth-appendages and the four pairs of walking legs, but the form ofthe body is very different in the two groups, on account ofthe separation of the abdomen in the spiders pi-oper, by aslender stalk, and the presence at its extremity of the spin-nerets (Fig. 137). Some of the chief structural peculiarities of the spidersmay be gathered from Fig. 138. The two-jointed cheliceriBterminate in a powerful claw, perforated by the duct of a. I Fig. 13S.—^Diayramiiiatic section of aspider—Epcifu. (After Etuerton). a, h, upper and lower lips ; c, a3soi)hagus; d, /, upper and lower muscles of the suck-in;^ stomach; e, stomach ; (j, lif^auieiits attached to diajjhragni under the stomach ;k, upper, j, lower, lurve-jranijlion ; I, nerve to leys and palpi; m, in, branches cf stom-acli; n, poison-sland; o, intestine ; i), licurt; r, luny ; s, ovary; t, trachea; u, spinning^dLinds. poison-gland. Between the bases of the pedipalpi is the mouth,wliich leads by an oesophagus into a sucking stomach, dilatable bymuscles, and provided with lateral cceca. The abdominal part ofthe intestine is provided with a liver, and with Malphigian tubes(slender cceca arising ^from the hinder end of the intestine inair-breathing Arthropods, and discharging the function ofkidneys). The heart is elongated like that of the scorpion andof the lower Crustacea, but the nervous cord is concentratedinto the thorax. Above the oesophagus is the brain, which
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1889
