No. 4-] AMPHITHOK LONG1MAXA SMITH. 191 



while studying the reactions of the animal to olfactory stimuli, 

 and it was noticed that the regeneration of these appendages 

 took place with considerable rapidity. Several observations 

 were also made on specimens in which the antennae were 

 found to have been accidentally lost. In a specimen (Fig. 2) 

 observed August 13 the left antennule had been removed at 

 the end of the second joint, and the right one at the end of the 

 first. Of the second antennae the left member was off at the 

 end of the, fourth joint, which had a small, apparently regener- 

 ated knob at the end, and the right was gone at the end of the 

 third and had a black tip. On August 16 the specimen moulted 

 and the antennae appeared as follows : The right antennule 

 had regenerated the last two joints of the peduncle and a 

 flagellum of twelve joints ; the left antennule also had com- 

 pleted its peduncle and regen- 

 erated a flagellum of seven 

 joints, two of which were par- 

 tially constricted in the mid- 

 dle and may have later become 

 separated into two joints each. The second 

 antennae had both completed their peduncles, 

 the fifth joint in the right one being somewhat 

 longer than in the left. The left antenna as a 

 whole, however, was longer than the right, and its flagellum 

 consisted of nine joints, while that of the right was composed 

 of seven. How long the antennae had been injured when 

 the observation was first made I cannot state, but it was cer- 

 tainly since the previous moult, so these appendages were 

 probably regenerated in not much over a week and possibly 

 in a less time. In another specimen first observed August 

 13 the left antennule was gone at the end of the second 

 joint, and the right one at the middle of the second joint. 

 The left second antenna was off near the end of the fourth 

 joint, and the right one at the end of the third. After moult- 

 ing, which occurred on August 14 or 15, the right antennule 

 had a completed peduncle and a flagellum of six joints ; the 

 left antennule did not regenerate. Each of the second anten- 

 nae had a complete peduncle, and the left one had a flagellum 



