GASTEROPODKS. 269 
hue below. While crawling up the side of the vessel, its form was well 
displayed : the tentacula, with a fold or hollow in the upper part, 
much resembling « horse’s ear : the cornicula, rising erect from the neck, 
with the black eye near the base, and the cavity of the back open or 
closed, or surrounded by its protecting membrane. This animal extended 
just two inches. It afforded satisfactory delineations, from which its form 
and appearance are rendered very explicit. 
In another fine and healthy specimen, of about equal dimensions, or 
rather larger, the black eye was surrounded by a white line. 
This animal was quite vigorous, and fed copiously on the common 
green fucus. But I know not that such food was the most congenial, for 
it did not undergo much alteration by digestion. The creature's body 
was very transparent. 
This specimen always testified a disposition to rise to the surface of 
the water, where it swam supine ; or it would adhere by the tip of the 
tail to some solid substance, or to the glass, suspending itself in the water. 
It is a distinguishing habit of the Aplysia to suspend itself in this manner. 
A third specimen, towards the same size as the others, was very 
beautiful : the skin sparingly strewed with white specks, the animal 
plump and vigorous. I rate these animals as nearly equal, for they ex- 
tended twenty-four, twenty-five, and twenty-six lines respectively. 
White specks were also on the body of a smaller specimen, which fed 
copiously on some of the Floridez, and increased rapidly in size. Indeed, 
the colour of the species seems to indicate that the natural food is to be 
sought among algze of that description. This animal survived ten months ; 
it died suddenly, tinging the water purple. Sometimes a great quantity 
of water is so tinged by a single living specimen. 
None are easily preserved permanently. 
Pirate XXXVI. 
Fia. {. Aplysia depilans, profile. 
2. Upper surface. 
3. Under surface. Tentacula, a. Cornicula, 6. Branchial cavity sur- 
rounded by its protecting membrane, with a smooth purple mar- 
gin, ¢. 
