200 



THE AMERICA X XA I L'RALIST. [X'ol. XXXVIII. 



tank by themselves some facts were made out as to the sub- 

 sequent moultings durin^;- the rest of Ma\-, June and the first 

 half of July. These youn- had a large aquarium with good 

 supply of mud, Chara, anodons and various plants and insects 

 with running water, sunshine and shallow water for good aeration. 

 The young remained in the third stage for about i8 days and 

 their color gradually changed from red to greenish owing to the 

 great increase in the blue pigment. The legs also developed 

 bands of dark color across them though otherwise almost 

 invisible, yet the big claws stood out as reddish objects with 

 blue at the base. The fourth stage had about the same coloring 

 but being so much larger it was much more easily seen. The 

 rostrum-telson length was 12 mm.: the claws reached out 

 2 mm. in advance of the rostrum : the antennae were about 8 

 mm. long : the thorax was 2h mm. wide, and the tail-fan expanded 

 5^ mm. One of these lar\ a^ had short, simple papillae upon the 

 first abdominal segment to represent the pleopods, apparently of 

 the female. These young were still translucent enough to show 

 the beat of the heart, at a rate of about three beats to the 

 second, and the circulation of blood corpuscles in the antennas 

 and legs, though the muscles were now much more conspicuous. 

 The effect of the red pigment cells was everywhere toned down 

 by the widely diffused blue cells. 



In about 17 days, that is July ist, many of the young had 

 passed into a fifth stage. The length was now 15 to 18 mm., 

 with the thorax about 3 mm. wide and the tail-fan 8 mm. The 

 color of this fifth stage was white on the ventral side and else- 

 where this was overcast by greenish. The legs were now white 

 with dim transverse bands of gray while the large claws had 

 lost the red and showed brilliant blue at the base of both finger 

 and thumb. 



The young move about actively, in walking they move the 

 fore pairs of pleopods back and forth very rapidly. They swim 

 readily and are still shrimp like in movement and in appearance, 

 as they have long slender legs, protuberant eyes and wide tail- 

 fans. 



Within a week some larvae were found in a sixth stage with a 

 length of 21 mm., a thorax width of 5 mm., a tail-fan expanse of 

 1 1 mm. and antennae about 19 mm. long. 



