1 66 



ESTHER F. BYRNES. 



Herrick recognizes, also combines a one-jointed fifth foot with 

 two-jointed rami. It is known as C. affinis and is like C. pliale- 

 ratits, " which it closely resembles." 



A fourth and a last type to which I shall refer, is seen in a not 

 infrequently occurring form which combines twelve-jointed antenna: 

 with three-jointed rami in the swimming feet and a two-jointed 

 fifth foot (Fig. 5). 



Herrick recognizes three species as having these characteris- 

 tics, namely : C. capillatus and C. crassicaudis, both European 



FIG. 5- Shows a twelve-jointed antenna which is relatively very long as compared 

 with the cephalothorax, notwithstanding the relatively small number of antennal seg- 

 ments present. 



forms, and C. varicans, an American form. The two former are 

 described as Scandinavian forms only. Of the third species C. 

 varicans, Herrick says that it is " the American species most 

 nearly resembling the European form with twelve antennal seg- 

 ments and a two-jointed fifth foot." " Unhappily," Herrick also 

 remarks, " this species was taken but once." On Plate XXX. 1 

 Herrick figures the first foot of C. varicans, which he pictures as 

 having two-jointed rami in the swimming feet. Herrick explains 

 that the last joint is homologous to two fused segments, and that 

 the separation might take place " at the next moult." The form 

 I have studied shows the armature when the rami have reached 

 1 " Copepoda, Cladocera and Ostracoda of Minnesota." 



