405] AXOPLOCEPHALIDJE—DOUTHITT 55 



an unmodified vas deferens and to cease to have a purpose for existence 

 when the vas deferens comes to function as a storehouse for spermato- 

 zoa, as is the case in all other genera except Aporina. 



Within the genus Andrya there has been a wide range of evolution. 

 A. primordialis is decidedly the most primitive in structure of ovary 

 and uterus and testicular distribution ; and only in the arrangement of 

 genital pores is it unlike what should be expected in the ancestors of 

 all the Anoplocephalidae. In Andrya macrocephala and A. translucida 

 on the other hand is found a rather high degree of specialization. As 

 regards position in the scale Aporina is a close contestant with Andrya 

 for the most primitive position, each having distinct points in its favor. 

 Aporina must be regarded however as an offshoot since certain charac- 

 ters which it possesses exclude it from the direct line. 



From forms like the most primitive Andryae there sprang appar- 

 ently a line destined to give rise to all the other Anoplocephalidae, 

 except possibly Bertiella. The characteristics of this line, many of 

 which were subsequently modified, were as follows: 



1. The lobes of the ovary did not radiate from the point of attach- 

 ment of the oviduct, but instead extended out from a transverse bar 

 which formed the base of the ovary. 



2. The vagina and vaginal pore had begun to move anteriorly and 

 ventralwards. 



3. The testes had come to lie mostly in the posterior part of the 

 proglottid. 



4. The cirrus pouch had begun a conspicuous development in size, 

 foreshadowed in Andrya primordialis. 



5. The female glands remained in the primitive position, near the 

 median line. 



6. The prostate gland was lost and the vesicula seminalis was 

 acquired. 



The genus Anoplocephala apparently separated from the rest early, 

 and developed along somewhat different lines. It retains the following 

 Andryan characters. 



1. The uterus, in anlage, crosses the excretory ducts ventrally. 



2. The testes extend into the lateral field on the side away from 

 the pore. 



3. The proximal end of the oviduct lies beneath the median lobe 

 of the vitelline gland. 



4. The tendency towards dextral arrangement of genital pores is 

 retained and perfected. 



