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 papillae, 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 branchiae 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 in a 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 



