Occasional Papers of the Miisciun of Zoology 3 



Type Specimen : Cat. No. 161, Museum of Zoology, Uni- 

 versity of Michigan; taken from Perca Havesccns (Mitchell), 

 Lake Monona, Wisconsin; Sept. 22, 1917; A. S. Pearse, col- 

 lector. 



Description of 7'ype Specimen : This tapeworm is short but 

 robust. Its length (end-proglottid missing) is about 24 mm., 

 its greatest width about 0.9 mm. From the appearance of the 

 worm it seems doubtful if individuals ever attain a much great- 

 er length. The head, figures i and 2, is relatively broad and 

 short, measuring 0.310 mm. broad at the posterior margin of 

 the suckers while its length from the tip of the head to the 

 line along which the breadth was measured is 0.130 mm. At a 

 distance of 0.375 mm. from the tip occurs an expansion which 

 measures 0.423 mm. in width. The head is thin dorso-ventral- 

 ly. The rather long neck region is not well defined since it is 

 relatively broad and passes almost imperceptibly into the seg- 

 mented portion of the body. Traces of internal segmentation 

 begin at 3.5 mm. from the tip of the head, making the neck a 

 little more than 3 mm. long. It has no marked constrictions. 

 The earliest proglottids distinguishable in the preparation meas- 

 ure 0.489 mm. wide by 0.050 mm. long. The twenty-fourth 

 proglottid measures 0.733 "ii^i- broad by 0.359 ^^^""i- lo"''?- This 

 proglottid is rapidly approaching maturity, testes are nearly 

 grown and the ovary is evident. The thirty-fourth proglottid, 

 figure 4, is mature. It measures 0.896 mm. broad by 0.245 mm. 

 long. The thirty-sixth proglottid has eggs in the uterine 

 branches. With the production of eggs and their storage in the 

 uterus the proportions of the proglottids gradually change 

 from broader than long to longer than broad. The forty-ninth 

 proglottid, figure 5, is 0.880 mm. wide by 0.782 mm. long while 

 the fifty-ninth and last proglottid in the chain, figure 6, meas- 

 ures 0.733 "I"''- broad by 1.304 mm. long. The terminal or 



