92 The Rev. P. Keith on the Structure of Animals. 



aversion to strong-scented plants *. Around the head there 

 are fixed a number of arms, which are the organs of locomo- 

 tion and of prehension. In Sepia officinalis they are ten in 

 number, two of them being longer than the rest. The arms are 

 furnished with suckers, in the shape of excavated tubercles, by 

 which the individual can fasten itself firmly to external sub- 

 stances, and thus stand, as it were, upon its head. The Sepice 

 have the peculiar property of ejecting at pleasure from the ab- 

 domen an inky-coloured fluid, that darkens the water in their 

 vicinity, and renders them for a time invisible to their pur- 

 suers. They are not uncommon on the coast of England. 



Class 2. In the second class we have the slug, that infests 

 our gardens and corn-fields during the spring and summer, 

 devouring the radicle, or the cotyledon, or the tender blade of 

 the young plant, and blasting the golden hopes of the too san- 

 guine cultivator. The largest of the tribe, when extended, may 

 be about the size of a finger. The head is furnished with a 

 mouth, by which the individual gathers its food ; and with a 

 pair of horns, or feelers, terminating each in a black point, 

 which is regarded as an organ of vision. It slides along upon 

 its abdominal surface by a sort of vermicular movement, 

 leaving a slime behind it; and it has the capacity of contract- 

 ing its extended body into a very small compass, if affected by 

 fear or hastily interrupted in its peregrinations. 



Class 3. In the third class we have the oyster in its shell, 

 the delight of the gourmand, or connoisseur in sauces, and so 

 well known to every lover of good things as scarcely to stand 

 in need of any description. It belongs to the order of acepha- 

 lous bivalves, having its abode in the ocean, but choosing as 

 its favourite habitat the mouths of rivers or of estuaries. It 

 sheds its spawn in the month of May on rocks and stones or 

 other substances at the bottom of the water, to which the young 

 brood clings till detached by the industry of the dredger, to 

 be transported to beds calculated to forward their growth and 

 give additional delicacy to their flavour. The oyster seems to 

 be destitute of all organs of locomotion, and yet it is capable 

 of changing its place. By opening its shell to a certain width 

 it takes in a portion of water, which it has the power of squirt- 

 ing out again with considerable force, and in any direction, 

 and of thus propelling itself to any point in a direction con- 

 trary to that of the force exerted. 



Division III. The Articulata. — The third division of 

 animals in the descending scale is the Articulata, which have 



* Carus, Compar. Anat., i. 74, by Gore. 



