METAMORPHOSIS OF CORYSTES CASSIVELAUNUS. 473 



of the carapace is fringed with a number of setjB, The 

 appendages have now taken on essentially the form of those 

 of the adult. The second antennae are considerably longer 

 than the carapace, many-jointed, and provided with the 

 characteristic dorsal and ventral row of set^. The antennas 

 have, as already described, the same function of serving as a 

 respiratory tube as they have in the adult. The mandible 

 palp is now three-jointed, the distal joint bearing a number 

 of setge and overhanging the mouth opening in front. 



The first maxilla differs from that of the preceding stage 

 in the form of the endopodite, which is now not jointed, and 

 bears but a single well-developed seta. This reduction in the 

 number of setas is remarkable from the fact that in the adult 

 there is a rich clothing of sette. 



There is but little change m the form of the inner lobes, 

 and the only change from this stage to the condition in the 

 adult consists in a relative reduction of the superior lobe and 

 an increase in number of spines. 



In the second maxilla there is a great increase in size of 

 the scaphognathite and simplification of the structure of the 

 endopodite (fig. 12). 



The first and second maxillipedes show an intermediate 

 condition between the swimming limb of the zoasa and the 

 masticatory limb of the adult. The two-jointed exopodite is 

 practically unchanged, except that in the first pair it bears 

 but five terminal seta), and in the second pair eight. The 

 endopodite of the first pair (fig. 15) is no longer jointed, but 

 has not acquired the lamellate form characteristic of Corystes. 

 The two basal joints are richly setiferous at their inner 

 margin, and the epipodite is greatly developed. The endo- 

 podite of the second maxillipede (fig. 17) has practically the 

 adult form, Avhile the podobranch and small arthrobranch 

 are both developed. 



The third maxillipede develops directly to the adult form, 

 the second joint of the endopodite having the characteristic 

 anterior prolongation. The remaining thoracic legs have in 

 all essential respects the form of those of the adult. The 



