50 ILLINOIS BIOLOGICAL MONOGRAPHS [50 



ones quadrate or a little longer than broad. The intersegmental fur- 

 rows were not plain. The measurements of the proglottids in a glycer- 

 ine specimen examined by the writer were as follows : First proglot- 

 tids 0.370 mm. broad by 0.170 mm. long, middle and mature proglottids 

 0.680 mm. broad by 0.390 mm. long. The last proglottid in the strobila 

 was the longest, measuring 0.650 mm. long by 0.460 mm. broad at ante- 

 rior end. The segmentation is not evident. The proglottids are joined 

 by their full breadth and the transverse furrows between the segments 

 are very shallow. No longitudinal furrows are present. Drawings of 

 three regions (Figs. 61, 62, 63) show the proportions of the segments 

 at anterior, post-middle, and posterior region. 



The genital pore, not marked by a papilla, is marginal, irregularly 

 alternating in the strobila, and is situated about the middle of the pro- 

 glottid. The cirrus-sheath is relatively very long and slender, for it 

 extends about to the middle of the proglottid. Its length in the broad- 

 est proglottids is about 0.230-0.250 mm. Schneider reports that its 

 inner end lies very near the dorsal muscle layers. This is also the case 

 in P. percae, P. pinguis La Rue, P. exiguus La Rue and a number of 

 other Proteocephalus species. The cirrus runs through the cirrus-pouch 

 in a sinuous course without the formation of a vesicula seminalis. The 

 vas deferens forms a fairly large mass of coils in the middle of the 

 segment. This mass however is much smaller than in P. fallax La Rue 

 or in P. exiguus La Rue. Schneider found about 30 testes in each seg- 

 ment, lying in a single layer, about 8 in a transverse row, and they 

 measured 0.080-0.090 mm. in sagittal by 0.040-0.050 mm. in frontal 

 diameter. It has been found difficult to count the testes in the more 

 mature proglottids. Thirty-eight testes are shown in nearly mature 

 proglottids (Fig. 62) while in the younger proglottids where they are 

 smaller and more easily distinguished the writer counted 44-48-52. The 

 testes seemed to be in two partial layers filling the area between the 

 vitellaria. The larger testes measure as much as 0.070-0.080 mm. tho 

 the larger number measure about 0.050 mm. Schneider found the 

 diameter of the two ventral excretorv vessels to be about 0.015 mm. 

 and that of the two dorsal about 0.0025 mm. 



The vagina (Fig. 62) opens anterior to the cirrus-pouch. Very 

 near the opening, 0.030 mm. from it, is a sphincter muscle 0.015 mm. 

 thick, according to Schneider. The writer was unable to observe this. 

 From its opening the vagina as a broad tube describes a long smooth 

 curve to the middle of the proglottid, then it bends posteriad and 

 passes back to the interovarial space. As the vagina nears the middle 

 of the segment the lumen becomes constricted. Early in its course it 

 crosses the cirrus-pouch diagonally. The vagina is dorsal to the uterus. 



