. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Branchiomaldane vincenti 153 The lobate brain, oesophageal connectives, non-ganglionated nerve- cord (without giant fibres), and eyes are similar to those of a young Arenicola. Statocysts are absent. The earlier statements regarding the nephridia of I>. vincenti give the impression that there is considerable variation in the number of these organs. Prof. ]\Iesnil (1897) referred to the presence of pigmented segmental organs in the 5th, fith, 7th and 8th chae- tiferous segments, and, in 1898, stat
. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Branchiomaldane vincenti 153 The lobate brain, oesophageal connectives, non-ganglionated nerve- cord (without giant fibres), and eyes are similar to those of a young Arenicola. Statocysts are absent. The earlier statements regarding the nephridia of I>. vincenti give the impression that there is considerable variation in the number of these organs. Prof. ]\Iesnil (1897) referred to the presence of pigmented segmental organs in the 5th, fith, 7th and 8th chae- tiferous segments, and, in 1898, stated that four or five pairs were present; Prof. Fauvel attributed three to five pairs of nephridia to this worm, but Drs. Gamble and Ash worth found only two pairs, opening on the fifth and sixth segments. The writer has examined five specimens in regard to their nephridia, and in all of them only two nephridiopores could be seen, situated immediately ventral and posterior to the fifth and sixth neuropodia. P)y means of serial sections of two specimens and by dissection of anotlier it has. X 90 Tiff. 66.—B. vincenti. Diagram of the nephridia of Uie left side, seen from the inner (median) aspect. The crotchets of the flftli, sixtli, seventh, and eighth neuropodia (v, VI, vii, viii), and the external openings (', ) of the Hrst and second nephridia' are indicated. been proved definitely that only two pairs of nephridia are present but the second is continued l)ackwards, beyond its pore, as far as the eighth or ninth neuropodium, where it ends l)lindly (Fig. 66). The gonads are situated on the coelomic epithelium, especially of the oblique muscles and septa. All the specimens examined by the writer were hermaphrodite. The oocytes fall into the coelomic fluid at an early phase of growth ; their later growth-phases are found chiefly in the posterior segments, the coelomic cavities of which, in mature specimens, are practically filled with large oocytes (Fig. 67). When fully m
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