| OCR Text |
Show 1905.] GEPHYREAN WORMS OF ZANZIBAR, ETC. 29 1G being Sipunculids and 4 Echiurids. Of the Sipunculids three, and of the Echiurids one, are new; the latter, a Thalassema, presents the novel feature of four pairs of nephridia, the greatest number hitherto met with in that genus. Unfortunately the Echiurids are not at all well preserved, and it is evident that the preservation of these animals needs even more careful attention than in the case of the Sipunculids. In this group, moreover, I notice that, whether due to contraction or otherwise, the nephridia and anal trees are apt to lose their characteristic appearance, the nephridia appearing small or even absent, and the anal trees simple in a species in which they are really dendritic. S l P U N C U L I D A . I. Genus S ip u n c u l u s . 1. S ipu n c u lu s in d ic u s Peters. Arch. f. Anat. u. Pliys. p. 382 (1850). Loc. Pemba Island. I f ah. From the eastern reefs in sand near the shore. Two large specimens, the internal organs of which are not sufficiently well preserved to enable me to add anything to our knowledge of their general anatomy. 2. S ipu n c u lu s e d u l is Lamarck. Sluiter, Natuurk. Tijds. Nederl. Ind. xlv. p. 484 (1886). Loc. Chwaka Bay, Zanzibar. /lab. Shore at low tide. Several examples; in one of which the transverse dissepiments are absent. 3. S ipu n c u lu s c um an en sis K e f . Selenka, Die Sipunculiden (Semper's Reisen, iv. p. 104). Loc. Chwaka Bay, Zanzibar. Three specimens corresponding with Grube's var. semirugosus. Loc. Zanzibar. Two specimens of var. vitreus. 4. S ipu n c u lu s t itu b a n s Sel. & Biilow. Selenka, tom. cit. p. 57. Loc. Chwaka Bay, Zanzibar; two large specimens. This is a very clearly defined species, and these specimens agree closely with the description. The only comment I have to make on the original account is that, so far at least as concerns these examples, the papillse on the introvert, though certainly " von dreieckiger Form," are not so obviously so as in the case of S. indicus: the angles are rather softened down. This character together with the relative positions of the nephridial and anal |
