ie NUDIBRANCHIATA.—TRITONIADA. 
fragile in their structure, and although many—in- 
deed I may say numbers—were caught, yet very 
few in comparison were found to be in a perfect 
condition, some being deficient in one, two, or more 
fins, and others being completely crushed. Not 
one of the specimens caught on this occasion, or 
during the voyage, had the silvery line or streak 
running down the back, from the head to the ex- 
tremity of the tail, branching off also to the fins, 
and along the centre of each of the digitations. 
Several Porpite were also captured in the net at 
the same time with these animals, and served as 
food for them. 
“Tt caused much regret to see the change death 
produced in the beauty of these interesting little 
animals, and all means of preserving them were 
found to be useless. When placed in spirits, the 
digits of the branchial fins speedily became re- 
tracted ; the beautiful purple gradually faded, and 
at last disappeared, and the delicate pearly white 
of the under suriace of the body and fins peeled off 
and disappeared. Thus did this beautiful Mol- 
lusk become decomposed in less than the space of 
an hour. Some Mollusks quickly lose their colour 
after death, but retain their form for a long time; 
but these speedily change after death, both im form 
and colour, and the beauty before so much admired 
perishes, never to be regained. 
‘¢ When taken in the hand, the under surface of 
the animal soon becomes denuded of the beautiful 
pearly white it previously had, and at that time 
appears like a small transparent bladder, in which 
a number of air-bubbles are observed, together with 
the viscera. On the abdomen being laid open, a 
large quantity of air-bubbles escaped; and perhaps 
