1914] A New Cestode from Amia Calva L. 97 



cirrus and vagina. The fact, however, that the epithelium of the genital 

 ducts of this species seems to be almost entirely a syncitium, even in the 

 mature proglottides, should have special emphasis at this point. 



The cirrus and vagina open very close together (actually from 0.02 

 to 0.07 mm. apart) on the ventral surface, about two-fifths of the length 

 of the proglottis from its anterior end, in that part of the strobila where 

 the auricles define the extent of the joints and relatively much farther 

 forward posteriorly where proglottidation is absent (Fig. 17). This 

 latter is partially due to the developing uterus-sac pushing them farther 

 forward. There is no genital sinus, although in some states of contrac- 

 tion a more or less well-defined depression into which the two ducts ap- 

 pear to open, much resembles one, — in fact in some proglottides the cirrus 

 and vagina open into each other on the ventral surface. The opening 

 of the uterus is to be found on the ventral surface also, just ahead of the 

 posterior end of the uterus-sac. 



All of the reproductive system is accommodated in the medullary 

 parenchyma, and, excepting testes and vitelline glands which are situated 

 peripherally, the latter immediately within the longitudinal muscles of the 

 parenchyma, all parts are much elongated antero-posteriorly, an adapta- 

 tion apparently to the narrowness of the strobila. The limbs of the ovary 

 are even squeezed together, making the whole organ horseshoe-shaped. 



The "generative space", that is, the space enclosed by the limbs of 

 the ovary, is filled with the proximal ducts of the female system (Fig. 27). 



Male System 



In young proglottides, in which the uterus-sac is short and narrow, 

 the testes are from 55 to yofj, in diameter and almost spherical in 

 shape (Fig. 18), while in those in which the uterus is gravid they are 

 ellipsoidal and from 70 to 115/z long. Opposite the distended uterine 

 cavity and near the reproductive ducts behind and forward they are more 

 or less flattened — in the former position, greatly flattened (Fig. 19). 



Like the vitelline glands the testes are continuous from one proglottis 

 to the next. They are separated into two lateral fields by the medially 

 situated genital ducts but come together in front and behind these, in the 

 interprogiottidal regions, to form a layer, also divided by the median 

 excretory vessel (Fig. 18). This layer, which is situated in the medul- 

 lary parenchyma, is made up of as many as six testes, in cross-section, 

 three on each side and all in the medial coronal plane of the body. No 

 more than one testes at a time is seen on each side of the section through 

 the gravid uterus-sac (Fig. 19). In mature joints it is difficult to say 

 how many testes there are, but from the posterior edge of the ovary of 

 one set of genital organs to that of the ovary of the next there are about 

 40 in each lateral field, or about 80 in all (Fig. 17). 

 8— 



