FIG. I. Shows the antenna and fifth foot of a cyclops with thirteen-jointed an- 

 tennae, A, A', Group I. The antenna and fifth foot of a cyclops with fourteen 

 jointed antennre, B, B / , Group II. The antenna and fifth foot of a cyclops with 

 seventeen-jointed antennae, C, C / , Group III. D shows the abdomen, the recepta- 

 culum seminis and the caudal stylets characteristic of all the forms with thirteen, 

 fourteen or seventeen-jointed antennre. E shows the large ramus of the maxilliped 

 characteristic of the three forms. B also shows the tenth antennal segment in the act 

 of dividing, thus giving rise to the fourteen-jointed antenna. 



As compared with the length of the cephalothorax all the antennae A, B and C 

 shown in Fig. I are relatively long, extending to the first segment irrespective of the 

 number of segments they contain. 



