i9ii] Watson: The Genus Gyrocotyle. 38] 



setosa, the presence of an operculum in uterine eggs must be 

 adopted as ;i specific characteristic of G. nigrosetosa. 



In addition to those characters which have been proposed and 

 found trustworthy, the writer suggests the following: 



1. Tin character of tfu folds of tht terminal rosette, whether 

 simph or complex. This is correlated with the greater relative 

 size of the rosette; but the fact that the size varies greatly and is 

 difficult to express in a ratio that could lie applied to any speci- 

 men to be determined, makes the character of the folds them- 

 selves seem a more easily applicable test. The write]' is convinced 

 that this character is constant in all stages of contraction, at all 

 ages, and after treatment with all the ordinary reagents. It 

 becomes unrecognizable only after decay has proceeded very far 

 indeed. 



i'. Tin rutin between tin distanct from tin opening of tin 

 nil rim to tin tip of tin acetabulum, mnl tin distanct from the 

 opening of tin uterus In tin lint of tin opening of tin pi ins. 

 While these absolute distances vary enormously with the state of 

 contraction, a series of measurements shows that the ratio is 

 fairly constant about a mean characteristic of the species. 



Table I. 

 Ratios of Measurements of Position of Genital Pores in Gyrocotyle. 



»«(Wag.l G. nigrmetoti 

 .4615 .333 .490 



.4500 

 .4444 

 .4444 

 .4375 

 .4375 

 .4295 

 .4295 

 .4295 

 .4290 

 .400(1 

 .4000 

 .3809 

 .3333 

 .3333 

 .3333 



