. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . Acrosoma gracilis (nigosa), A. saggittata (spinea), and A. rc(lu\iaiia(mitratii). WEAVERS OF ROUND WEBS. 127 downward and snstained by the feet, tlie difference being, as already noted,that the Epeira clasps with her feet the meshed terminations of the radiiwithin the hub, while Acrosoma supports herself by the margin of the openhub. In the case of Rugosa, the method isthe same but the position of the spider a littledifferent. The two h
. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . Acrosoma gracilis (nigosa), A. saggittata (spinea), and A. rc(lu\iaiia(mitratii). WEAVERS OF ROUND WEBS. 127 downward and snstained by the feet, tlie difference being, as already noted,that the Epeira clasps with her feet the meshed terminations of the radiiwithin the hub, while Acrosoma supports herself by the margin of the openhub. In the case of Rugosa, the method isthe same but the position of the spider a littledifferent. The two hindermost legs are claspedto the upper margin or to the bit of ribbonedlace that frequently runs upward from the hubof the spiral space. The back or dorsum ofher abdomen thus hangs towards the spinnerets are turned upwards and assistto support the spider by a little dragline. Thehead in this position is of course depressed,and at an angle say of forty-five degrees, moreor less. She supports this part of her body notonly by the first and second pair, but Position j^jg^j |j ^l^g ^l^| .^|j. Qf 1p„j, which,of Third ?^ ^ t, > > Fig. 112. Acrosoma mitrata suspend-ed at the hub of her orb. FourthLegs. ^^ contrary to the custom of Orbweaversgenerally, are thrown forward on either side of the face. Generally the third pair of legs is correlated with the fourth pair, and the second with the first, but here the third is associated with the first fact is doubtless in some way connected with the peculiar ^°^^ character of the fourth legs, which in the genus Acrosoma are as long as or longer than the first legs. The length of the fourthpair is an evident convenience to the spider when walking; for the ventral part of the abdomen is an inverted pyramid or cone, at the apex of which the spinnerets are placed. The ad-ditional length of the fourth legs thus servesto raise these organs above the ground as thespider moves. The same reason, viz., thelength of
Size: 1281px × 1950px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookidamericanspid, bookyear1889
