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Show 1901.] FROM BRITISH EAST AFRICA. 341 resemble those of P. violacem. The accompanyiug drawings (text-fig. 84) show their considerable variety of form, which is very striking wheu a portion of the contents of the spermathecal sac is teased out iu glycerine. Claparede \ as is well known, at first mistook the spermatophores of Tubifex for a parasitic organism which he termed Pachydermon, a mistake which was later rectified by himself and by Bay Lankester \ Had Claparede made Ins discovery upon the present species, the mistake would have been equally natural. For these remarkable spermatophores, when of large size, are invariably twisted and coiled, precisely like Text-fig. 84. Spermatophores of Polytoreutus hindei, greatly magnified. a bunch of parasitic jVematoids, which animals do occur iu the tissues of earthworms. The vermiform appearance of the spermatophores is shown in the drawing (text-fig. 84). There are, however, many of the spermatophores which are much smaller, and I have selected a series to illustrate the main varieties which I have observed. The small spermatophores may subsequently grow;, though I have noticed no signs of immaturity about them or evidence of any kind that they do grow while within the spermathecal sac. The complicated coils into which some of the spermatophores have thrown themselves seem to m e to indicate the strong possibility that they are motile. There is no doubt whatever that the 1 "Etudes Anatomiques sur les Annelides, Turbellaries, Opalines et Grega-rines observes dans les Hebrides," M6ui, Soc. Phys. et Hist. Nat. Geneve, xvi. 1861, p. 88. 2 " O n the Structure and Origin of the Spermatophores or Sperm-ropes of Tubifex," Quart. Journ. Micr. Sci. xi. p. 189. For a fuller account of the literature of the spermatophores in the TubificidaB, see Vejdovsky's ' System u. Morph. d. Oligochaeten,' Prag, 1884, p. 151. PROC ZOOL. Soc-1901, VOL. I. No. XXIII. 23 |