no. 1404. 



I\ [JIA SITIC COPE PODS— CA Lid ID- E— WILSON. 



537 



through them. On either wide at the center are two large spots of the 

 pigment, which characterizes the particular species. This varies 

 decidedly in color and pattern in the different species thus far exam- 

 ined and will probably furnish a useful means of identification. 



There are other much smaller spots of the same pigment, which vary 

 somewhat in location in the different species, but are usually found, 

 one on either side, close to the posterior end of the body, and a median 

 unpaired spot just above the eye. 



Of the appendages the first antennas are uniramous and terminate 

 in two long plumose setse. They are often carried close together and 

 pointing straight forward in front of the nauplius. The second 



Fig. 37.— Early nauplius of Caligus bonito, dorsal view; pigment cinnamon brown in a 

 continuous line around the margin of the body. 



antennae and mandibles are biramous, the exopod four-jointed, each 

 joint bearing a long plumose seta, the endopod with a single joint ter- 

 minating in two .similar seta'. These three pairs of appendages pro- 

 pelled by the powerful muscles already noted make 1 efficient locomotor 

 organs, and the nauplii move rapidly. And even at this early stage 

 some difference can he seen between the nauplii of the different 

 species. Those like Caligus rapax, which are very active in the adult 

 form, begin this activity in the early nauplius. while others appear 

 comparatively sluggish. 



Near the posterior end of the body there is a pair of appendages 



