. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . ra diademata. (After Under- dredth of an mch is the average length ^^^^ , posterior spinning neid; , ducts of the silk duct. On the-posterior pair of the treeform glands ; , pyriform glands„ . , 1 i • J. J. 1. with their ducts, du; , the middle spinning of spmnerets are about sixty tubes; on spools in middle pair, although the spinnerets are smaller, about eighty. The spools on these two pairs are alike, but
. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . ra diademata. (After Under- dredth of an mch is the average length ^^^^ , posterior spinning neid; , ducts of the silk duct. On the-posterior pair of the treeform glands ; , pyriform glands„ . , 1 i • J. J. 1. with their ducts, du; , the middle spinning of spmnerets are about sixty tubes; on spools in middle pair, although the spinnerets are smaller, about eighty. The spools on these two pairs are alike, but they differ in shape from those of the anterior pair and are much larger. There are nearly two hundred and twenty spools on the anterior pair, thus making altogether three hundred and sixty on the six spinnerets. Spools Blackwall also made the discovery that the number of spools arywi ^^..^^.-^g ^.-^j^ ^j^p .^g^, ^j q-^q female. In specimens of Drassus ater, which had attained nearly a third of their growth, they amounted to five or six. In others, which were two-thirds grown, to six or seven. In adults which had acquired their full complement, they. -mss 50 AMERICAN SPIDERS AND THEIR SPINNINGWORK. were unilnnuly eight, two of whicli were situated on the inferior surfuceof tlie spinneret at a greater distance from the extremity tliau tlie rest,and were minute and ahnost contiguous. It is a fact deserving notice that tlie spiuuing spools are not alwaysdeveloped simultaneously on these spiimerets, six, seven, and eight beingsometimes observed on one, while five, six, or seven are to be seen on theother. This remark is applicable not to the anterior spinnerets alone, butto tiic intermediate ones also, which, in mature individuals, are furtherniodilicd by having the extremities of the terminal joints directed forwardsat ri compression of surround
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Keywords: ., bookcentury1800, bookdecade1880, bookidamericanspid, bookyear1889
