NEW TAPEWORMS FROM THE HYRAX. 581 



The vagina opens on the exterior behind the aperture of the 

 cirrus sac and immediately contiguous to it. As will be men- 

 tioned in describing the cirrus sac there is no common cloaca. 

 The direction of the tube from its opening into the receptaculum 

 seminis is obliquely backward, the external pore lying at the side 

 of the segment posteriorly. The terminal portion of the vagina, 

 the length of which is not far from equal to that of the cirrus sac, 

 is somewhat dilated and with a wider lumen ; it is plainly ciliated. 

 The whole of the vagina is very muscular, the muscular layer 

 being as thick as that of the cirrus sac. The lining epithelium 

 is deeply stained. The course of the vagina is very straight until 

 it bends somewhat at its entrance into the large receptaculum 

 seminis. The latter is bent round the outermost of the two longi- 

 tudinal water vessels. From its opposite end arises the wide 

 common duct, which after a short course divides into the posterior 

 vitelline duct and the anterior oviduct. The two latter are in 

 the same straight line. 



A closer examination, however, of the long muscular vagina 

 shows that it is really divisible into two regions. These are 

 inequisized, the larger section being that which is nearer to the 

 external pore. This section has a much wider lumen than the 

 ensuing section, which opens into the wide and thin-walled 

 oviduct. The la,tter has a narrow thread-like lumen, but still 

 thick and muscular walls. It is not so long as the distal region 

 of the vagina. This part corresponds to the very short and 

 suddenly abbreviated part of the vagina in ThysanoUenia 

 gambiana ; but is obviously very much more developed. It is 

 not in the same straight line as the wider distal section of the 

 vagina, but bends back to meet the forwardly running oviduct. 

 This division of the vagina appears to be very characteiistic of 

 the present species. 



At the time that I was preparing my account of the anatomy of 

 the two species of my genus Thysanotcenia I was not acquainted 

 with Janicki's memoir upon his genus Inermicapsifer, and therefore 

 laid no stress upon some structural features which are of 

 importance in comparing these forms. I have therefore carefully 

 re-examined my sections of Thysanotcenia gambiana, and made in 

 addition several series of fresh sections, in order the better to 

 accomplish this comparison. By these means I am in a position 

 to make a few corrections in, and additions to, my earlier 

 account. 



I find that account, however, to be correct in all essentials, 

 excepting with i-egard to the presence of a vesicula seminalis 

 in the neighbourhood of the ovaiy. This was doubtfully 

 asserted, however, and I now find that the structure in question 

 is really a part of the dilated and thin-walled oviduct, which runs 

 straight, as I have said, from the thick-walled region near to the 

 external pore and gradually increases somewhat in width as it 

 approaches the ovary. I confirm my account of the variability 

 in the lateral extension of the ovary and vitelline gland, which 



