52 ILLINOIS BIOLOGICAL MONOGRAPHS [402 



of development ; but there is no evidence that there intervenes a trans- 

 verse tubular stage which is comparable in any sense to the uterus of 

 Anoplocephala. 



On the other hand it seems much more probable that the reticulate 

 uterus has been derived by lateral spreading from a median longitu- 

 dinal uterus, such as we find in more primitive cestodes, and is the first 

 step in the evolution of the transverse uterus rather than the last; that 

 the tubular uterus of Anoplocephala has been the product of simplifi- 

 cation. Schizotaenia seems to be in an intermediate condition ; the 

 uterus appears in a widely diffused condition but the cavity appears 

 first as an anterior transverse tube. Some such view becomes necessary 

 if Andrya is regarded as a primitive type, as other characters indicate. 

 It is a matter of sincere regret to me that other matters prevent making 

 a careful study of the uterus at this time. 



Aporina, Andrya, and Anoplocephala agree in that the uterus, in 

 nearly all species, extends laterad beyond the excretory ducts, crossing 

 them ventrally. Never does it cross them dorsally in anlage and at all 

 stages it lies mostly ventral. In Schizotaenia, and apparently always 

 in Bertiella, it is confined to the median field in mature proglottids 

 and in its fully developed stage crosses the ducts mostly on their dorsal 

 side, if at all. In Cittotaenia and Moniezia the uterus in anlage usually 

 crosses both excretory ducts dorsally but in some species is confined at 

 all stages to the median field. Apparently it never penetrates between 

 the excretory ducts and the ventral cortical layer. These points fur- 

 nish very important indications of the relationships of the varied genera 

 to each other. The development of the uterus by outpocketing must 

 be recognized as a very general character of the subfamily, and in 

 general, a primitive one. It has been shown to be the method of devel- 

 opment in Andrya, where it was supposed not to occur, and in one 

 species of Schizotaenia. 



2. The Distribution of Testes. — The genus Aporina has been con- 

 sidered unique in that the testes extend laterad beyond the excretory 

 ducts. In the present paper however are described four species of 

 Andrya and two of Anoplocephala in which the testes do extend across 

 the excretory ducts on the side away from the pore, and in the other 

 species of Anoplocephala here taken up they do in many proglottids. 

 Likewise, Zschokke's figures for Bertiella edulis (1899, Taf. XX, Fig. 

 2) shows that in this species the testes may extend nearly across the 

 ducts. It seems probable that they occur in the lateral fields in all or 

 nearly all species of Anoplocephala and Andrya, and in the median 

 field in all species of Schizotaenia and most species at least of Bertiella. 

 The double pored genera of course, cannot be compared in this regard. 



