GASTEROPODES. 309 
cula to the extremity of the tail, The body rather of a broad lanceolate 
figure, the shoulders prolonged in slender processes, endowed with tenta- 
cular action. Back bare in the middle, clothed with four large bunches 
of long slender branchial papillx, crossing each other towards the lower 
extremity of the animal when quiescent, and bristling up when suffering 
any annoyance. They are more numerous in proportion to the size of 
the specimen. The clusters on the shoulders of one consisted of thirteen, 
and on that of a smaller specimen, it consisted of eight. Head round, 
with the mouth wide and conspicuous, towards the front of the face be-_ 
low. The cornicula, about half the length of the tentacula, are indented 
on the upper part by about twelve whirls. At the root of each a very 
black speck denotes the eye. Colour universally delicate carnation of 
different shades ; the central line of the branchie red ; the whole ex- 
tremities of the animal tipped with white. 
On September 3, when the thermometer at ten o'clock morning and 
evening stood at 66° and 70° respectively, the pulsations at the heart 
were just sixty ina minute. They are very conspicuous in this animal. 
The Porcupine Doris shews several peculiarities. It does not shun 
the light ; its six appendages all exercise a kind of tentacular faculty. 
Its adhesion is slight, though its mucous secretions are abundant ; but, 
above every thing, its voracity, so different from the usual habits of the 
Doris, is most remarkable. It fed voraciously on mussel, and on the 
periwinkle, whereof large portions being swallowed entire, the back rose 
in proportion to the quantity. The quality of the food also was disclosed 
by the transparency of the skin, which was very evident on one occasion, 
when a black Planaria was thus devoured. 
It cannot have escaped the notice of practical observers, how seldom 
it is that the food of any of this numerous tribe can be ascertained, and 
how often all that we can provide is rejected. They are not commonly 
understood to be carnivorous ; but the subjects of this paragraph were 
eminently so, for they sometimes gorged themselves to such an excess, 
as to be scarcely capable of moving. Contrary to the nature of most 
living animals, they seemed ready to devour their own species. 
In six or seven weeks after capture, only two of the original six 
