OCR Text |
Show 208 MR. F. E. BEDDARD ON THE OLIGOCH^TE [Mar. 6, subfamily of the Eudrilidae (Pareudrilacea) *, extend from segment vi. to xii. inclusive. The septa which lie between segments v./xii. are very thick ; those which divide the two following segments are moderately thick and are at least distinguishable by their size from those which follow. It is noteworthy that the septa which enclose segment xiii. approach each other very closely in the middle of the body in immature examples which I have examined in glycerine after dividing them longitudinally. This is not infrequent in the ovarian segment of earthworms. Although the female reproductive organs were more or less fully developed in two out of the five examples which I studied of this species, I a m not able to give a complete account of their structure. There is, however, a median spermathecal sac which opens upon the thirteenth segment to the exterior. This is connected with an egg-conducting apparatus, as in other species of the genus. It is largely the asymmetry of the female generative apparatus which leads me to refer the present species to the genus Stuhlmannia; though it is, of course, not this feature alone which has influenced me. There are obviously other points of similarity. In his account of both Stuhlmannia variabilis and S. gracilis Michaelsen has not noticed the asymmetry f. In examples of a species which I regarded as belonging to that species + I commented upon the fact that the receptaculum ovorum of one side of the body was rudimentary. In a more recent and more exhaustive account of the female reproductive system of the genus, and as I thought of the same species, viz. AS'. variabilis, I described at length § the same series of facts. Still later I found || in a third species of the genus, viz. S. michael-seni, the same asymmetry. There is some discrepancy in the three accounts given by m e of the asymmetry which possibly are not real discrepancies. I have described in some cases the left and in others the right side of the apparatus as partly rudimentary. In the species which forms the subject of the present communication there is no doubt that it is the right side which is fully developed and the left receptaculum ovorum which is rudimentary. This agrees with m y account of Stuhlmannia michaelseni and with m y earlier statement as to the matter contained in the " Monograph." If there is an error I a m not now able to rectify it. But I can say positively that in Stuhlmannia inermis I found the receptaculum to be rudimentary upon the left side of the body. The median spermathecal sac gives off a branch upon each side which passes * Beddard, Quart. Journ. Micr. Sci. vol. xxxvi., n. s. f " Beschreibung der von Kerr Dr. Fr. Stuhlmann auf Sansibar und dem gegen-iiberliegenden Festlande gesammelten Terricolen," Jahrb. Hamb. wiss. Anst. ix. (1891) and " Die Regenwiirmer Ost-Afrikas," in Deutsch Ost-Afrika, Bd. iv. t A Monograph of the Order Oligochajta (Oxford, 1895). | " On some Earthworms from British East Africa," P. Z. S. 1901, vol. i. p. 351. || " On a new Genus and Two new Species, &c," P. Z. S. 1903, vol.' i. p] 212*. |