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Show 1892] SPICCIES OF EARTHWORMS. 669 be (woodcut, fig. 1) ; these setae are also absent from the xviith and trom the xixth segments, or rather they are there replaced by the penial setae. In all the species of Acanthodrilus, on the other hand, which 1 have been able to examine, the ventral setae are not missing trom the xvmth segment, though they are not present on the xviith Fig. 1. 1 XVI At At Segments bearing atrial and sperm-duct pores in a number of Acanthodrilids. A. Octochcetus antarcticus; B. Acanthodrilus capensis ; C. Benhamia (any species); D. Acanthodrilus smithi; E. Acanthodrilus novce-zelandice. At. atrial pores ; 3, sperm-duct pores; the groove connecting the atrial pores and the sette is indicated ; penial setae are omitted in D and E. The segments are numbered. and xixth segments, being there replaced by the penial setae; this is also the case with the genus Octochcetus; in two of the species of that genus at any rate, viz. 0. multiporus and 0. antarcticus (woodcut, fig. 1), the ventral pair of setae of segment xviii. are PROC. ZOOL. Soc-1892, No. XLV. 45 |