127] PROTEOCEPHALIDAE—LA RUE 127 



agree at all with the measurements made by Schneider or the writer. 

 Neither Kramer nor Zschokke give measurements of the head and suck- 

 ers but they state that the head is large, the suckers large and round. 

 Nufer's specimens which infested Perca fluviatilis most certainly could 

 not have been P. torulosus (Batsch) but were either P. percae, P. fallax 

 La Rue, or an undescribed species. 



Batsch drew the head of P. torulosus as a broad structure with large 

 and prominent suckers. His figures which have been reproduced (Figs. 

 145, 146) should be compared with the drawing of a head (Fig. 7) 

 derived from material sent to Professor Ward by Professor Levander. 

 There is remarkable agreement in form of head and of suckers. The 

 thick neck is about 2-3 mm. long by about 0.20-0.30 mm. broad. It is much 

 wrinkled thus making difficult the determination of the length. It 

 passes over gradually into the first proglottids which are much broader 

 than long. Mature and ripe proglottids are almost always broader 

 than long. The maximum length observed was 1.0 mm. and the maximum 

 breadth 2.5 mm. Many nearly ripe proglottids measure about 0.29 

 mm. long by 1.30 mm. broad. The proglottids are thick and fleshy with 

 well defined limits. Indentations between the proglottids are deep and 

 the corners of the latter are quite pronounced. The end proglottid is 

 rounded posteriorly. At its posterior end it has a deep indentation 

 into which the excretory ducts discharge. 



According to Kramer the excretory ducts in the head and neck 

 region are very prominent with many anastomosing coils. In the neck 

 region he found many branches of the excretory vessels leading to the 

 exterior. Sections made by the writer failed to show these relations. 



The genital openings are irregularly alternating, and are situated 

 near the middle of the margin of the segment. The vagina opens not 

 strictjy anterior to the cirrus-pouch but somewhat dorsal thereto. Kra- 

 mer incorrectly states that the vagina and cirrus-pouch open near each 

 other but not into a common atrium. The testes are large, spheroidal 

 or by pressure they may be sometimes rendered polyhedral. They 

 measure according to Schneider about 0.160 mm. in sagittal by 0.080 

 mm. in frontal diameter. My measurements are about the same as 

 these. The testes lie in two layers, the dorsal layer (Fig. 78) covering 

 the entire area bounded by the vitellaria and the anterior and pos- 

 terior margins of the proglottid. Thus the ovary is completely covered 

 by the dorsal layer of testes about 70 in number. In the more ventral 

 layer there are about 30-40 testes. Hence the total number of testes is 

 about 100-110. Kramer's drawing (Fig. 184) shows a small number 

 of testes but since it shows the ventral view of the worm it cannot show 

 a large number. The coils of the vas deferens form a thick mass ex- 



