NOTES ON THE VARIATIONS OF RHEGMATODES. 



375 



than the ratio I have found in Anrdia (op. cit.\ it may still be 

 doubted whether it sustains any direct selectional value to the 

 species, any more than in the case of Anrdia. 



GONADS. 



The gonads are closely correlated with the radial canals, form- 

 ing a double fold along the line of each canal. In not a few 

 cases it was found that the gonads of certain canals were more or 

 less rudimentary. Whether this may have been due to arrested 

 development, or to some wholly unrecognized cause it is impos- 

 sible to say. As a rule, it may be said that in those canals 

 marked by incompleteness, as in Figs. 2, 3 and 4, the gonads 

 were of this character, i. e., showed signs of arrested develop- 

 ment, or atrophy. An apparent exception was observed in the 

 case shown in Fig. 7, where in the loops formed the gonads were 



FIG. 9. Showing variations 

 in branching, etc. 



FIG. to. Showing spurs. 



larger and better developed than those of the normal canals of 

 the same specimen. I think an explanation of this condition 

 may be found in the fact that here the short loops of the canals 

 were in closer connection with the gastric pouch, and thus pro- 

 vided with a larger food supply than in either of those of such 

 incompleteness as shown in Figs. 2-4, or indeed the normal 

 canals. Aside from these rather incidental aspects of variation 

 there was little to call for special emphasis, or fuller details. 



