. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. Spiders. GENERAL CLASSIFICATION AND STRUCTURE. 23 Palps. rotary motion upon the fore part of the sternum, moving toward and against each other, thus crushing the interposed prey. The palps (ps) or palpi arc two organs inserted into the free end of the maxillae, of which they are an organic part.^ Each palp has five joints of various lengths named in order from the maxilla, (1) axillary, ax, (2) humeral, hu, (3) cubital, cu, (4) radial,
. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. Spiders. GENERAL CLASSIFICATION AND STRUCTURE. 23 Palps. rotary motion upon the fore part of the sternum, moving toward and against each other, thus crushing the interposed prey. The palps (ps) or palpi arc two organs inserted into the free end of the maxillae, of which they are an organic part.^ Each palp has five joints of various lengths named in order from the maxilla, (1) axillary, ax, (2) humeral, hu, (3) cubital, cu, (4) radial, ra, and (5) digital, dg. The axillary joint is the shortest of the five and corre- sponds to the second joint of the leg or trochanter, the maxilla being the equivalent of the coxa.'^ The humeral joint is much longer than the axillary; the cubital again is short, being a sort of knee joint. The radial is one and a half or twice as long as the above, and the digital is usually the longest joint of all.'' The palps vary greatly in the two sexes. In the female each digital, dg, ter- Sexual minates like the foot Forms of i . ,, , Pains ^ ^® usually armed with a well developed curved claw (palpal claw) pec- tinated or serrated. These or- gans are prehensile, are used va- riously as hands or feet to hold and turn the prey, to dig, to sustain the body when suspend- ed upon webs, to grasp the CO- pm. W. Male of Agalena noevia: the speckled Tubewcaver. coon, etc., and even to aid in (Marx, dei.) locomotion. In the male the digital joint contains the genital organ; it is enlarged, often very greatly, into a bulb whose structure is complicated and subject to great specific variations. (Fig. 12.) It is always more or less covered on top by a plate, which may be distinguished from other parts by a more or less dense pubescence scattered u^jon the superior surface and. ^ On account of the curved process upon the top of each maxilla whose convexity is toward its fellow, the palp may be said
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectspiders, bookyear1889
