ITS HABITS. 73 



and changes much in appearance by its various 

 degrees of contraction and expansion. Fig. 4 is a por- 

 tion of fig. 3 more carefully drawn, and more enlarged. 



Of the two specimens found, one was rather paler. 

 In captivity they were sluggish, fond of hiding 

 among the fronds and leaves of Delesseria and Iridcea; 

 but at times gliding freely like a Doris. They swam on 

 the surface by the foot reversed, and then left behind 

 a great wake of clear viscid jelly. They were beauti- 

 ful animals. After keeping them in health about a 

 fortnight, I put one into fresh water to kill it, for 

 preservation. This, however, was not so readily fatal 

 to it as I had supposed, for at the end of half an hour I 

 found by its contraction when touched, that it was still 

 alive. Probably the mode in which it had contracted 

 on being put in, the foot being narrowed, and the 

 edges of the mantle being incurved on all sides around 

 the foot, may have in some measure prevented the 

 access of the water to the vital parts. At the end of 

 that time I replaced it in sea-water, when it soon 

 partially recovered its activity, relaxing its mantle, 

 and contracting it dorsally so as to expose the 

 sulcus between it and the foot greatly, protruding the 

 tentacles and veil, and the branchial plume. Thus I 

 was enabled to get a much better sight of these parts. 



As soon as it was replaced in the sea-water, a 

 quantity of white mucus was discharged from the 

 whole surface, most copiously from the foot, which 

 as it lay on its back, was uppermost. This mucus, 

 gradually, by the contractions of the animal, was 

 accumulated in a knob at the posterior end of the 

 foot, and then thrown ofi". The reticulate structure 



H 



