22 PROCEEDINGS OF THE ACADEMY OF [Jan., 



Forbes considers the armature of the swmiming feet "of con- 

 siderable value in certain cases, and constant as a rule;" that 'Hhe 

 general character with regard to strength, etc., may usually be relied 

 upon; but I have often seen in a single specimen all the gradations 

 between spines and setse, and it would be impossible from this 

 character to say which of the two names should be applied." The 

 more I have worked out the armature of the swimming feet, the more 

 I am convinced that a constant standard cannot be obtained for 

 such an armature for all members of the same species. The following 

 table is an illustration of the confusing results obtained in attemjjting 

 to establish a standard "swimming-feet armature for C. phaleratus. 



Case Number 1, 



First pair — outer ramus, three spines, five setae; inner ramus, one 



spine, four setse. 

 Second pair — outer ramus, four spines, four setse; inner ramus, one 



seta, one spine, four setse. 

 Third pair — outer ramus, four spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Fourth pair — outer ramus, three spines, five setse; inner ramus, one 



seta, two spines, two setse. 



Case Number 2. 



First pair — outer ramus, three spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Second pair — outer ramus, four spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Third pair — outer ramus, four spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Fourth pair — outer ramus, three spines, five setse; "inner ramus, one 



seta, two spines, two setse. 



Case Number 3. 



First pair — outer ramus, four spines, five setse; inner ramus, one 



spine, four setse. 

 Second pair — outer ramus, four spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Third pair — outer ramus, four spines, five setse; inner ramus, one 



seta, one spine, four setse. 

 Fourth pair — (right) three spines, five setse; inner ramus, one seta, 



two spines, two setse. 

 Fourth pair — (left) four spines, four setse; inner ramus, one seta, 



two spines, two setse. 



The above cases show a variation in both outer and inner ramus 

 of the first pair, in the outer ramus of the second pair, and the outer 



