304 CHARLES ALBERT SHULL. 



No. 2. C. (Bartoniits] bartoni, d\ The third right appendage 

 was cut off March 24. On May 9, no moult having occurred, 

 the stump of the appendage was cut longitudinally by means of 

 sterilized scissors. The moult occurred on June 17, but no 

 abnormal growth was noted. The appendage was perfect, and 

 showed regeneration of more than 50 per cent, in size (Fig. 1 1). 



No. 5. C. (Bartonius] bartoni, 9. The second left appendage 

 was removed March 24, 1907. The first moult occurred on 

 May 8, 1907, and the regeneration amounted to about 30 per 

 cent. The second moult took place on June 26, 1907, when the 

 appendage showed about 65 per cent, of complete regeneration. 

 Fig. 1 2 shows the point of amputation, and Fig. 13 the appendage 

 after the second moult. 



No. 6. C. (Bartonins] bartoni, d\ Sixth right appendage was 

 amputated just beyond the basal joint March 27, 1907, as shown 

 in Fig. 14. It moulted the following day. A very narrow edge 

 of white tissue was visible along the cut edges, but it is not 

 probable that any regeneration had taken place. During the 

 time preceding the next moult which occurred on May 27, the 

 basal portions of the rami increased somewhat in size (Fig. 15), 

 and after moulting the appendage was about one half natural size, 

 and perfectly formed (Fig. 16). 



A series of experiments on the pleiopods of Paltzmonetcs vnl- 

 garis was carried on at Cold Spring Harbor, and regeneration of 

 all the abdominal swimmerets takes place rapidly in young 

 specimens. 



At present a series of experiments to test the regeneration of 

 the antennse from various levels and to compare the rate of 

 regeneration of pleiopods and pereiopods in C. (Bartonius] bartoni 

 is being carried on ; but the data are insufficient as yet to permit 

 a general statement regarding either phase of the series. 



DISCUSSION. 



A. The Abnormalities : As far as I have been able to ascer- 

 tain, only one abnormal abdominal appendage has been recorded 

 for any of the decapod crustaceans. In as much as all abnormal 

 pleiopods described herein or elsewhere have been discovered 

 accidentally, the rarity of such records is due in part, perhaps, to 



