166 ILLINOIS BIOLOGICAL MONOGRAPHS [166 



diameter and are situated on the four quadrants of the head. The four 

 quadrants are somewhat swollen and are separated from each other by 

 longitudinal furrows. The apical depression is a true sucker, as is shown 

 in the stained specimen. There is no neck, the first segments appearing 

 under the microscope 0.060 mm. behind the margin of the suckers. The 

 size relations of the proglottids have already been given. From the 

 drawing, reproduced (Figs. 128, 129), the strobilation is evident, the 

 posterior angles of the proglottids being quite prominent. 



The anlagen of the sexual organs may be seen 7 mm. back of the 

 tip of the scolex while the well developed testes may be seen 3 mm. farther 

 posteriad. These are elliptical in shape, their long axis lying in the 

 long axis of the worm. They number 70-100, and lie irregularly scat- 

 tered between the vitellaria and anterior to the ovaries. They are most 

 numerous in the lateral fields but they may also occur in the median 

 part especially in the anterior region. No data are given concerning the 

 cirrus-pouch and the vas deferens. The genital pore is irregularly 

 alternating. It is situated near the middle of the margin of the seg- 

 ment, but in the last proglottids a trifle anterior thereto. 



The vagina opens posterior to the cirrus-pouch. Just before its 

 opening it possesses a considerable broadening, the diameter of which 

 is about equal to the broadest diameter of the cirrus-pouch. On either 

 side of this broadened part the vagina is narrow. The vitellaria are 

 lateral longitudinal glands which develop late. They are not volum- 

 inous. The bi-lobed ovary lies in the posterior part of the proglottid as 

 in Proteocephalids. Since the uterus was immature in this species the 

 eggs could not be observed. 



This species easily separates itself from the most of the forms, 

 parasitic in fish, by reason of the large size of its head and suckers. 

 The position of the vagina posterior to the cirrus-pouch is a further 

 diagnostic character of value, while the lack of an unsegmented neck 

 and the proportions of the proglottids are characters which serve for 

 its identification. Unfortunately Klaptocz failed to describe and to figure 

 the cirrus-pouch, cirrus, and vas deferens which are of great value in 

 making a positive determination. The uterus being immature could not 

 be described. For these reasons this species which probably is a species 

 of Proteocephalus cannot be accurately placed in its relation to the 

 other members of the genus. 



