A study of the extent to which the anomuran Porcellana platycheles will autotomize its legs on single stimulation of successive appendages has shown (Hoadley, 1934) that there is a clear-cut and fundamental difference between the behavior of males and of females bearing eggs. This form is ideal for such experiments in that gently seizing the leg between the points of blunt forceps will ordinarily be followed by auto tomy. Males tested in the above fashion autotomized an average of 5.57 + legs per animal (69.6 per cent) , the distribution of the autoto mies being 4 for the first four trials and 1.57 + for the second four. Quitein contrasto this,thegravidfemalescastanaverageof two legs in the eight trials (25 per cent) , the distribution being 1.5 and 0.5 in the first and second four trials respectively. Unfortunately but one female not bearing eggs was available at the time of the examination of this material, but a test of that animal showed five legs autotomized (62.5