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Show 684 MR. F. E. BEDDARD ON NEW [Dec. 20, an opening into the gut. This arrangement, however, occurs in Lumbricus, where it was first, I believe, accurately described by Messrs. Marshall and Hurst in their ' Practical Zoology'; but it has not been described in any other genera, and most certainly does not exist in many Earthworms, e.g. Pontoscolex (=Urochceta), where each gland opens by its own duct into the oesophagus. The calciferous gland of the xvth segment has a rather smaller development of the internal folds ; the duct leading to the oesophagus is ciliated. The intestine begins in the xviiith segment. Another feature of interest in this genus concerns the male efferent apparatus, which differs in detail from that of many other Earthworms ; the male pores are upon segment xvii. within the ventral pair of setae; each aperture is really double, though this point is not recognizable without having recourse to section-cutting. The two apertures of each side are enclosed by the swollen epidermis, of which the cells are very elongated and at the same time narrow; one aperture lies in front of the other; the anterior of the two is connected with the atrium, and through it project a few penial setae which are enclosed in a muscular sac ; these penial setae have the form illustrated in Plate X L V I . fig. 13. The atrium is not in any way remarkable; it belongs to the tubular type and is divided, as in Acanthodrilus, & c , into a granular and a muscular portion. The vas deferens near to its external opening, in fact from segment xv. onwards, is enveloped by a thick muscular coat which is fully as thick as is that of the atrium. I have already described in Pyg-mceodrilus a similar muscular investment of the terminal region of the sperm-duct; and I have met with the same thing in two species of Benhamia described above. The nephridia of this worm are diffuse. The position of the male pores distinguishes the genus from Digaster, in which the male pores are upon segment xviii. O n the other hand, it is quite possible that it is congeneric with Dichogaster as extended by Michaelsen to include his new species D. minus and D. hupferi. The particular points referred to in the above description are not mentioned by Michaelsen ; accordingly it is uncertain how far I a m justified in creating a new genus. III. Genus PERIONYX. This genus was founded by Perrierl for a worm closely related to Perichceta, but differing from that genus by "the development of the clitellum, the arrangement of the male orifices, the position of the spermatothecae, and finally the clearness of the segmental organs." Although the investigations of Perichceta which have been carried out since Perrier's paper was published have led to a necessary alteration of the wording of the above quoted phrase, there is every reason to agree with Perrier in holding the genus Perionyx as distinct from Perichceta. There is at present no reason for 1 " Eecherches pour servir a l'histoire des Lombriciens, &c," Nouv. Arch. du Museum, t. viii. p. 126. |