48 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



stitutes the "tail-fan," shows no lateral appendages. These do not 

 develop until the third stage. 



Second Larval Stage. 



When the young lobster has moulted for the first time in its exist- 

 ence, and has entered the second stage, many characterisitc changes 

 form the first larval stage may be observed; it is now somewhat 

 larger, measuring about 9 or 10 mm. (% in.). In the region of the 

 head these differences appertain chiefly to the first and second pairs 

 of antennse. The inner portions, or the endopodites of the first pair 

 have grown out from the mere buds existing in the previous stage, 

 to half the length of the exopodites or outer portions. These latter, 

 at this period, have developed tufts of setse which are supposed to 

 have an olfactory function. On both stalks, inner and outer, slight 

 traces of segmentation are now observable. The endopodites are 

 still the larger and thicker of the two branches. (Plates VIII, XIV). 



In the second pair of antennse the endopodites have by this stage 

 grown out to equal the length of the broad, ciliated, leaf -like exopo- 

 dites, and segmentation is developed to a greater degree than in the 

 previous stage. In the case of the ambulatory appendages, chelipeds, 

 and maxillepeds, there has been a forward shifting of the complete 

 set, so that the body origin of the chelipeds is relatively anterior to 

 the position in the first larval stage and is approximating to the 

 adult position. The other appendages (maxillepeds and walking 

 legs) have shifted to a correspondingh^ anterior position. The 

 chelae or large claws, now relatively somewhat larger, have under- 

 gone U slight change whereby they more resemble the' adult type. 

 No difference between left and right can at this time be determined. 

 The exopodites of all these appendages are still functional to a high 

 degree. 



In this second stage the abdomen is characterized by the swimming 

 appendages, or swimmerets, on the under side of the 2nd, 3rd, 4th, 

 and 5th abdominal segments. There is as yet, however, no sign of 

 the appendages modified for reproductive function on the first ab- 



