150 ILLINOIS BIOLOGICAL MONOGRAPHS [150 



mm. anterior to the ovary. Benedict (1900) stated that there was 

 no uterine passage in this species. An examination, however, of his 

 slides and reconstruction drawings convinced the writer that a uterine 

 passage was present in Benedict's specimens as it was in his own. The 

 vitellaria are lateral and follicular. In this species they do not extend 

 posterior to the lobes of the ovary nor do they parallel the posterior 

 margin of the proglottid. The uterus in young proglottids is a median 

 ventral tube from which later 15-20 lateral outpocketings develop on 

 either side. Benedict's drawing reproduced (Fig. 183) shows but a 

 part of the pouches. There are 1-2-3 preformed uterine pores. The 

 uterine eggs are covered with three membranes, an outer, thin hyaline, a 

 middle thick and granular membrane and an inner thin membrane 

 closely investing the embryo. The outer membrane which is not spher- 

 oidal but ellipsoidal measures about 0.036-0.043 mm. in length. The 

 middle shell is spherical 0.022-0.024 mm. in diameter. The embryo 

 measures 0.0168-0.017 mm. in diameter. 



The American forms which most resemble this species are P. per- 

 plexus LaRue and P. nematosoma (Leidy). The latter may be 

 the same as P. ambloplitis. P. perplexus, however, is distinguished 

 from P. ambloplitis by its smaller head, smaller suckers, thin- 

 ner and smaller strobila, by the smaller size and the different loca- 

 tion of its sphincter vaginae, by the posterior prolongation of its 

 vitellaria, by its much smaller cirrus-pouch, by its fewer coils of ductus 

 ejaculatorius, by its larger number of testes, and by the smaller size of 

 the eggs. P. ambloplitis greatly resembles P. nematosoma. It differs 

 from that species chiefly in the somewhat larger size of the head and 

 suckers. P. ambloplitis is larger than most of the old world species of 

 Proteocephalus and it differs from a large number of these in not pos- 

 sessing a fifth sucker. It resembles P. torulosus in the lack of a function- 

 al fifth sucker and in size. It may be easily differentiated from P. toru- 

 losus by reason of its larger head and suckers, by its sphincter vaginae 

 which for size and length is unique in the genus, by its more numerous 

 uterine pouches, and by the different arrangement of testes. 



P. ambloplitis may be distinguished from all other known species 

 of Proteocephalus by means of its extremely large sphincter vaginae 

 which because of its length and its extraordinary development is re- 

 markable. This species is also readily distinguished from all other 

 species of the genus by reason of the large number of coils of the ductus 

 ejaculatorius. 



