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Show 1906.] WORMS OF THE THIRD TANGANYIKA EXPEDITION. 209 round the intestine; but whether the two unite above or not, I am unable to say. The " bursa copulatrix," or terminal chamber of the spermathecal sac which opens directly on to the exterior, may or m ay not communicate directly with the chamber containing the ovaries. I have no evidence of the communication if it exists. But in any case the sac in which the ovaries lie is different from what is to be found in S. variabilis*. In the present species of Stuhlmannia the entire bursa copulatrix lies within a large sac, which reaches from septum to septum of the xiiith segment and completely roofs in the bursa. In this sac attached to the front wall of the segment I have found one ovary. There is no question here as in >S'. variabilis of a small sac enclosing the ovary and communicating by a slender duct with the spermathecal sac and its circumoesophageal diverticula. For this reason I regard S. inermis as a distinct species from S. variabilis. Dr. Michaelsen's recently described species Stuhlmannia asymmetrica t is apparently not to be confused with the present species, as indeed the different habitat Avould lead one to infer. That species has no penial setae at all. Considering that the specimens investigated by Dr. Michaelsen were in a more advanced stage of sexual maturity than those of S. inermis, penial setae, if present, would have been surely visible in some at least of the many specimens in Dr. Michaelsen's hands. But there is, furthermore, the important difference that the asymmetry in Dr. Michael-sen's new species is carried to a greater extent than in that described here; for the oviduct, receptaculum, and ovary are entirely aborted on the left side of the body, the right hand efferent apparatus of the gonads alone remaining. This feature serves at once to differentiate the two species. Nor does there appear to be a sac surrounding the atrium of the spermatheca, and possibly derived from it, which contains the ovaries, as in the form which I name here Stuhlmannia inermis. Michaelsen's species represents the last term in the series of species of Stuhlmannia in which asymmetry is developed. Metschaina tanganyikse, sp. n. I feel obliged to form a new species for some specimens of an earthworm on account of various characters to which I shall refer in the course of the following description. It seems to belong to Michaelsen's recently instituted genus Metschaina. This species is much like the Stuhlmannia just described, and, like that worm, was found in wet sand close to Lake Tanganyika. Its dimensions are rather less than those of the largest Stuhlmannia inermis, but quite as great as some individuals of the latter species. It has, too, the same bluish colour. I have examined this worm almost entirely by means of longitudinal * See Beddard, P. Z. S. 1901, vol. i. p. 354, fig. 87. f "Die Oligochaeten Nordost-Afrikas," Zool. JB. (Abth. f. Syst.) 1903, p. 467. |