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Show 490 MR. F. E. BEDDARD ON THE [Dec. 4, appeared to be equal and stouter than the more anteriorly situated trunks. The. description which Zenger gives of the reproductive organs is, as he himself admits, imperfect. The most important point which he mentions is the presence of spermatophores, which were little known at the time when he wrote. There is nothing in his description of the reproductive organs to distinguish Peloryctes inquilina from Clitellio ater. On the whole the identity or non-identity of Peloryctes inquilina with Clitellio ater must be for the present regarded as an open question, though I am disposed to think that they are identical. § 2. Anatomy of Clitellio. Generative Organs.-Claparede's account of the reproductive organs of Clitellio is by no means complete. He has confounded, as so many writers have done, the testes with the vesiculce seminales; the former organs are not described by Claparede. I find that the testes differ in no important particular from those of Tubifex; they lie (see Plate XXIII. fig. 1), as in that genus, in the 10th segment, into which open the funnels of the vasa deferentia; each organ is long and narrow, somewhat swollen at the base of attachment to the body-wall. The vesiculce seminales (testes of Claparede) were not, judging from Claparede's description, fully developed in any of the specimens studied by me. The 10th segment in one specimen contained a mass of developing spermatozoa about equal in size to a similar mass occupying a large portion of segment 11. In the latter case, however (Plate XXIII. fig. 3), the mass of developing spermatozoa was enclosed in a thin-walled sac abundantly furnished with blood-vessels which was confined to this segment, and did not extend back through several segments. The generative system of a young example of C. arenarius is depicted in Plate XXIII. fig. 1 ; it will be seen that the funnels of the vasa deferentia open into the 10th segment, but the cells of which they are composed are not ciliated. The vasa deferentia pass in a slightly sinuous course to the atrium, which opens externally, not far from the posterior border of the 11th segment. The atrium in the undeveloped condition is lined by a simple non-glandular columnar epithelium ; it is invested externally by a thin coat of muscles, outside of which is a tolerably thick layer of glandular peritoneal cells. The spermathecce lie in the 10th segment, and at this stage are simple pyriform vesicles. Upon the anterior face of the septum which separates the 11th from the 12th segment, and corresponding exactly in position to the funnel of the vasa deferentia, is a disk-shaped layer of columnar cells, which is evidently the oviduct; the cells at this stage are, like the cells of the vasa deferentia funnels, not ciliated. In the sexually mature animal the oviduct-funnels are extremely conspicuous (fig. B & Plate XXIII. fig. 2) cup-shaped organs, with abundant cilia. At the time that I made this observation, I was not acquainted with any observations upon the structure of the Tubificidae later than those of Vejdovsky *; I concluded 1 System u. Morph. d. Oligochaeten. Prag, 1884. |
