52 REPORT OF COMMISSIOXERS OF INLAND FISHERIES. 



and terminating quite often in a double point (plates X, XX), 

 while the convex curvature of the back has quite disappeared and 

 the tail is much broader. The first pair of antennse emerge in quite 

 the adult type, of nearly equal length. Each is definitely segmented 

 and bordered at the joints by short setae. The olfactory setae are 

 apparently limited to the inner side of the outer branches of the first 

 antennse. 



The second pair of antennse have undergone a tremendous de- 

 velopment since the third stage and now consist of a very long whip- 

 like portion of many segments and the leaf-like exopodite, which has 

 grown but little since the previous stage. The basal joints of this 

 second pair of antennse seem to have undergone a development so 

 that, by occupying a more anterior position, the antennae proper 

 are able to fold posteriorily along the side of the body. 



The chelipeds of the fourth stage larva are much larger and stronger 

 than those of the third stage, and whereas the latter hung down from 

 the body and were but slightly functional, the former are carried, 

 while swimming, extended straight before the head, and in case the 

 young lobster is disturbed are quickly raised in an attitude of de- 

 fence. There is as yet no difference between the claws of either side 

 of the body. Both, however, with the passing of the third stage, 

 come to the normal adult position, having their body origin at the 

 anterior end of the cephalo-thorax rather than in a position some- 

 what posterior, characteristic of the first three stages. (Plate XVIII.) 

 One characteristic feature of this stage is the fact that the chelipeds 

 and ambulatory appendages have lost in the recent moult, the swim- 

 ming branches, or exopodites. These may be still seen, however, as 

 functionless rudiments, mere stumps with no trace of setae, on the 

 ischium or third segment of the chelipeds and walking legs. (Plate 

 XXI.) The latter have become far stronger than in the previous stage 

 and readily support the young lobster when he seeks, as he now often 

 does, to crawl along the bottom or hide by burrowing in the sand or 

 under rocks. The anterior pair of walking legs are modified as claws 

 which serve for the purpose of holding prey or to assist in crawling in 



