Smithsonian miscellaneous collections . ms to be little support for Silvestris view that the second maxillaeof the diplopods are absent. Considering the general similarity of the diplopod head to thecranial capsule of other arthropods, and the evidence of fundamentalunity in structure between the several groups of progoneate myria-pods, the current view (see Attems, 1926) is here accepted that thediplopod head contains both the first and the second maxillary somites,and that the legless neck segment is the first body somite, homologouswith the first leg-bearing segment of the Symphyla. The leg
Smithsonian miscellaneous collections . ms to be little support for Silvestris view that the second maxillaeof the diplopods are absent. Considering the general similarity of the diplopod head to thecranial capsule of other arthropods, and the evidence of fundamentalunity in structure between the several groups of progoneate myria-pods, the current view (see Attems, 1926) is here accepted that thediplopod head contains both the first and the second maxillary somites,and that the legless neck segment is the first body somite, homologouswith the first leg-bearing segment of the Symphyla. The legs of thissegment are small and reduced by the loss of one segment in Sym-phyla ; in Pauropoda, if present at all, they are rudimentary ; in Diplop-oda they are absent. The genital apertures of the diplopods, we maytherefore conclude, are on segment VII behind the mouth, as in thepauropods and symphylids. The genital openings in both sexes of the diplopods are more orless closely associated with the bases of the legs of the genital seg-. J -^^QL^K L Fig. 19.—Diplopoda: external genitalia. A, Habrostrepus, male, sternum, legs, and penes of third body segment,posterior view. B, same, gonopods, anterior (under) surface. _ C, Eurynrns,male, sternum, legs, and penes of third body segment, anterior view. D, same,seventh body segment, ventral view, showing position of gonopods and , same, right gonopod, anterior (upi^r) surface. F, Parajulns impressus,female, ventral part of third body segment and appendages, anterior view, telop-odite of right appendage removed exposing gonopore on the coxopodite. G,Thyropygus, male, right gonopod, anterior (under) surface. H, same, penes,posterior surface. I, same, left gonopod, posterior (upper) surface. J, Para-iuliis impressus, male, third body segment and appendages of second segment,posterior view. K, same, appendages of second body segment, posterior , same, sternum and first gonopod of seventh body segment, anterior ,
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Keywords: ., bookcentury1800, bookdecade1860, bookidsmiths, booksubjectscience
