REPORT OF COMMISSIONERS OF ^INLAND FISHERIES. 53 



weeds or grass. They may also be used with the chelse as weapons 

 of defence. The posterior pair are modified with spike ends, so to 

 speak, and facilitate in crawling over the sand or rocks. 



The swimmerets of the second, third, fourth, and fifth abdominal 

 segments have changed from those of the preceding stage. They 

 are now larger and double bladed (having both exopodite and en- 

 dopodite) , and serve to propel the young lobster rapidly through the 

 water or assist in causing, with the agency of the tail, those back- 

 ward or forward leaps and darts which are most characteristic of the 

 fourth stage. The exopodites of the last abdominal segment have de- 

 veloped greatly since the third stage, and now in length equal the 

 telson itself. The whole tail-fan with all its portions is now fringed 

 with long, closely placed setae and resembles very closely the tail-fan 

 of the adult type. 



After the young lobster enters the fifth stage there are observed 

 few changes as it passes on through the succeeding stages. The 

 general body form of this stage is quite characteristic of the adult 

 tj'pe, and the later changes which occur externally are, save in the 

 development of the external organs of reproduction, of little signifi- 

 cance in the future life history of the lobster. There are some points, 

 however, which may be noted, not with reference to any definite 

 stage-change, but with reference to the future development as a 

 whole. Among these changes may be noted the increasing difference 

 between the relative size of the eyes and body. In the first larval 

 stage the eyes were very large and prominent, but in the course of 

 later stages they become less and less prominent until in lobsters 

 of great age and size, weighing ten or twenty pounds, the eyes are 

 frequently no larger than shoe buttons. There is, moreover, a gradual 

 thickening in the body of the lobster as the age increases. In the 

 male lobsters this thickening occurs in the region of the cephalo- 

 thorax, while in the female it is noted in the broadening of the ab- 

 domen which appears to widen for the accommodation and protection 



