208 ME. F. E. BEDDARD ON [June 17, 



much younger than the other, though outwardly no differences 

 were to be detected. In the youngest stage the ovaries are plain, 

 and completely fill two sacs situated on either side of the nerve- 

 cord and at some little distance from it. These sacs are evidently 

 those which Michaelsen discovered in P. kirimaensis. They also 

 correspond exactly to the similar sacs in Eudrihis, in some young 

 stages of which the sacs iia question are closed sacs and have no 

 outlet ; later, of course, as is well known, they communicate with 

 the spermathecal sac. Furthermore, these ovarian sacs, as they 

 may be conveniently termed, correspond exactly to sacs involving 

 the testis of each side in segment xi. I shall deal more at length 

 with the points of likeness presently. Into each sac opens the 

 oviduct by a conspicuous funnel, which has precisely the I'elations 

 to the ovarian sac that the sperm-duct funnel has to the testicular 

 sac (seminal sacs, sperm-reservoirs) in the same worm. Moreover, 

 the course of the o^aduct, which in this young stage has not 

 reached the exterior, is exactly similar to the course of the sperm- 

 duct. In both cases the funnel opens into the sac towards the 

 centre of the body, and the duct bends sharply upwards and 

 ceases at the body- wall at a precisely corresponding spot. The 

 ovarian sac is not only continuous with the funnel of the oviduct. 

 Its lumen is perfectly continuous with that of the spermathecal 

 sac ; the latter, however, in this very young specimen, is in a state 

 of immaturity. It consists of a median sac as usual which 

 contains no lumen ; it is of inconspicuous dimensions, and runs 

 for a short way beneath the nerve-cord. Its latei^al branches, as 

 has been said, oj)en into the ovarian sac, and these branches have 

 therefore for a certain distance a lumen. The development of the 

 spermathecal sac is then, as it appears, from before backwards, 

 I could find no trace of a receptaculum ovorum as distinct from 

 the chambers of a ccelom already mentioned ; and in any case the 

 packing of the ovarian sac with a plug of germinal cells and 

 developing ova shows that the time for the transference of the 

 latter to a receptaculum was not yet ripe, and none of the ova 

 were approaching maturity. 



The existence of but one funnel seems to show that the exist- 

 ence of the funnels in the adult is simply a question of the 

 division and pulling out of one branch of the single funnel. 

 Furthermore, the fact that the ovarian sac commvmicates freely 

 with the spermathecal sac, and that the receptaculum ovorum is 

 formed later, shows that the communication in the adult between 

 the ovarian sac and the one or the other of these two sacs is only 

 a difference of secondary importance due to the, different times at 

 which the several cavities cease to communicate with each other. 

 In the older stage, the relations of the various parts of the 

 egg- conducting apparatus were further advanced and naturally 

 different. The ovarian sac contained no ova or germinal cells at 

 all ; these are transferred en masse to the receptaculum, probably 

 as the latter is formed. But the sac itself is quite evident, and 

 communicates by a narrow chink, not at all conspicuous, with the 



