6 University of MicJiigan 



pieces on this slide appear to make up almost a complete worm. 

 Their combined length is about 25 mm. In respects other than 

 those mentioned this worm agrees with the type. 



On the same slide is an immature worm with somewhat re- 

 tracted head. Five suckers in fair agreement with the suck- 

 ers of the type may be distinguished. This specimen is assign- 

 ed to this species. 



One small worm from perch, Lake Monona, Wisconsin, 

 Pearse's No. 9/22/ 17-31, and another. No. 9/20/17-40, taken 

 from Lake Mendota, Wisconsin, probably belong to this spec- 

 ies. They are immature and the preparations are very poor 

 making it impossible to secure all desirable diagnostic data. 



Some headless fragments on another slide differ more wide- 

 ly from the type than do the preceding specimens. In these 

 fragments the proglottids are narrower and longer, the ovarian 

 lobes much shorter and more rounded, testes more numerous, 

 intersegmental furrows less pronounced. Some of these frag- 

 ments may be referred to this species but one fragment at least 

 cannot. 



In the material from Pcrca Havesccns in Professor Ward's 

 collection are a number of fragments which can be readily 

 assigned to this species. Some of the larger specimens and 

 complete worms have been studied in detail and their meas- 

 urements are here given. 



Specimen No. 12.1470 of Ward's collection is immature. Its 

 head is 0.134 mm. long and 0.178 mm. broad. Its four suck- 

 ers measure 0.077 to 0.082 mm. in diameter and their cavities 

 are from 0.046 to 0.056 mm. in diameter. The fifth sucker has 

 a diameter of 0.034 mm. The neck, which is narrowest just 

 back of the head, has a length of 1.26 mm. The first proglot- 

 tids are 0.320 mm. broad by 0.012 mm. long. 



A considerably more immature worm than the preceding is 



