1914] A New Cestode from Ami a Calva. hi 



with growth, so that eventually, in gravid joints, the wall appears as a 

 very thin membrane, showing practically no structure (Fig. 19). In 

 slightly younger stages than that shown in Fig. 17 the lumen is not so 

 uniform in outline, since its anterior half is divided into shallow evagina- 

 tions, somewhat comparable to those seen in the uteri of the species of the 

 order Tetraphyllidea. These soon become obliterated, however, the 

 inside of the wall in gravid conditions begin quite smooth. 



The opening of the uterus-sac, situated, as shown in Fig. 10, towards 

 its posterior end, seems to function for a short time only, since in the 

 longest strobilas no trace of it was found near the end of the chain. In 

 the middle region, on the other hand, it appears as a very narrow slit, 

 about o. I mm. in length, in only a few proglottides. Furthermore the 

 uteri in which these openings are to be seen are generally almost free of 

 eggs, as if the openings had been used for the dispersal of the eggs in the 

 usual manner among the Bothriocephalids, while those behind the region 

 in question are tensely filled. These facts would lead one to think that 

 in most proglottides the eggs are freed by the rupture of the uterus and 

 the body-wall, as in the higher cestodes, beginning with the Tetraphyl- 

 lidea, while the uterine aperture either functions for a short time only or 

 in proglottides, probably more or less constant in number and location. 

 Fig. 31a is a view of the opening drawn from a transparent preparation 

 in the uterus of which were comparatively few eggs. It is seen that the 

 slit is surrounded by a clear area beyond which there is a more deeply- 

 staining region. The latter is in reality made up of radially arranged 

 nuclei which are related to the clear area in a manner better shown in 

 coronal sections of stages prior to the breaking through of the slit (Fig. 

 31b). Here they are seen to be connected with the dark line, where 

 the slit will appear later, by fine striations which continue farther out 

 into the surrounding cytoplasm. Whether these radiating nuclei form a 

 glandular organ around the aperture or give evidence of a migration from 

 the clear area which remains as a cuticular rim, is difficult to say; but, 

 from the close resemblance to the structure of the cirrus and of the en- 

 trance to the vagina, the writer is inclined to the latter view. 



Development of the fertilized ovum, which begins, as mentioned 

 above, in the uterine duct proceeds in the uterus-sac, eggs, bearing on- 

 cospheres, being obtainable from proglottides situated towards the pos- 

 terior end of the strobila. 



The e g g of this species is an ellipsoidal structure, from 60 to 70/i in 

 length and from 40 to 43 y. in breadth. The shell is uncolored and 

 perfectly transparent, so that the contents can be observed quite easily 

 (Fig. 32). It is lined by a very delicate membrane which, however, can 

 be seen only when it is, in some cases, separated from the former (Fig. 33). 



