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Show 364 ON EARTHWORMS FROM BRITISH EAST AFRICA. [Apr. 16, earlier account of this species, and of a few corrections in matters of detail. The larger of two examples examined measured 72 m m. by a greatest diameter of 2 m m . The worm is thus quite as slender as Gordiodrilus elegans, and the more robust form of the original specimens is perhaps merely a matter of greater contraction. The openings of the two pairs of spermiducal glands is, as correctly stated in the original description of this worm, upon segments ' xvii. and xviii. As to internal characters, it has been noted that this is the only species of Gordiodrilus which possesses a gizzard. The structure of this part of the alimentary canal shows some further peculiarities which have not yet been referred to. The gizzard in segment viii. has quite stout muscular walls, but the lining of cuticle is not strongly developed as is the case with earthworms where the gizzard is a prominent structure. Moreover, the gizzard by no means occupies the whole of the viiith segment; the last one-fourth or thereabouts is occupied by a portion of oesophagus, which differs from other parts of that tube iu that the muscular layer is rather thick, about as thick as the epithelium lining it. There is thus evidence that the gizzard of this species is in a state of degeneration. In segment vii. there is a similar thickening of the muscular walls of the oesophagus, the layers being again about as thick as is the epithelium beneath them. Here, therefore, is another, and a rudimentary, gizzard to be taken account of. The species seems to be descended from some form in which there were two gizzards in vii. and viii., and while one of them has nearly disappeared the other is commencing to undergo reduction. These facts further emphasize the bond of union between the genus Gordiodrilus and its ally Nannodrilus. though in a different way from the likenesses shown between Gordiodrilus papillatus and Nannodrilus. The genus Nannodrilus has two gizzards, which lie in the two consecutive segments vii. and viii. The facts, however, must apparently be interpreted on the assumption that from Nannodrilus arose two separate lines of descent, one represented by Gordiodrilus robustus, from which again 67. dominicensis can be derived as well as perhaps G. ditheca. The second line gave rise to 67. papillatus in the first place, from which may have arisen G. tenuis on the one hand and 67. elegans on the other. The relations of 67. zanzibaricus ' are not so plain as the others appear to m e at present to be. 1 It is necessary to emphasize this fact since some error has crept into my original paper upon tins genus in respect to the positions of the spermiducal gland-pores. 1 find on re-examination of m y preparations that in G. elegans the pores are correctly stated (upon pp. 84 and 9l>) to be upon segments xviii., xix., and incorrectly stated (upon p. 95) to be upon segments xvii., xviii. On the other hand, in G. dominicensis the same pores are, as in (i. robustus, upon xvii., xviii., as correctly stated on the table on p. 9f) of ray memoir; they are incorrectly stated upon pp. 91 & 94 to be upon xviii., xix." - As a small matter it m a y be well to note that " Gordiodrilus mattkewsi," spoken of on p. 453 of the M o n . Olig., is not, as Michaelsen has suggested, a lapsus pennce for G. robustus but for 6V. zanzibaricus. |