REPORT OF COMMISSIONERS OF INLAND FISHERIES. 229 



EXPLANATION OF PLATES 30 AND 31. 



Third larval stage; length, 1L.5 mm.; age, 9 days. 



First antennae: 



The endopodites have grown out to nearly the length of the exopodites; 

 both are now as long or longer than the rostrum; the olfactory setae are 

 very distinct on distal portion of the inner margin of the exopodites; 

 the segmentation of both exopodites and endopodites is clearly observ- 

 able at this period. 



Second antenn.e: 



The endopodites are now much longer than the exopodites; the latter 

 ■still retain their leaf-like form and extend beyond the tip of the rostrum; 

 the exopodites show definite traces of segmentation. 



Maxillipeds : 



As in second stage. 



Chelipeds: 



The claw portion approximates more clo.sely to the shape of the adult 

 claw; owing to a gradual torsion of the limb from the carpopodite 

 (fifth segment from base), the dactyl now opens upward and sometimes 

 slightly inw'ard. 



Ambulatory appendages: 



Much a,s in the third stage, except that the claws on the first two pairs 

 are more fully developed; the first segments of the last two pairs are 

 tipped with spurs; the exopodites are still functional. 



Abdo.minal appendages: 



These are now fringed with delicate setse, but are not yet functional; 

 the appendages of the sixth abdominal segment are now observable; 

 they consist of exopodite and endopodite of about equal size, both of 

 which are fringed with long setse. 



Tail: 



By the appearance of the appendages of the last abdominal segment the 

 tail now resembles .somewhat more closely that of the adult lobster; the 

 telson is bordered with a fringe of setse. 



