188 HALF AN HOUR WITH SHELL-FISH. 



to tear the part off than to detach the sucker. Each 

 sucker appears to be under the will and control of 

 the animal, and is formed on the principle of a 

 piston and cavity. When the sucker is applied, the 

 piston is withdrawn, and thus an air-tight adherence 

 is produced. The common sepia (Sepia officinalis) 

 has no fewer than nine hundred of these distinct 

 air-pumps or suckers. 



The Calamaries and Squids both of which occur 

 in British seas are distinguished from the "Poulpe" 

 or Octopus, by having ten arms, instead of eight. 

 These animals are found principally in the open sea, 

 to which habit of life they are well adapted by the 

 lateral fins on each side the neck, by means of which 

 they are assisted in rapid swimming. Their shell is 

 internal, and after death, is not unfrequently found 

 cast up on the beach. The internal bone of the 

 sepia is that commonly used in the manufacture of 

 tooth-powder. It is crystalline a structure which 

 is not absolutely destroyed by the severest crushing. 

 Under the microscope, with polarizing apparatus, it 

 forms a most beautiful object. They are the eggs 

 of this common species which may often be met with 

 among heaps of cast-up seaweeds. Among the fisher- 

 men they go by the name of " Sea-grapes " a not 

 inappropriate term, if we go by their "general appear- 

 ance. In Fig. 101 we have an illustration of these 

 cuttle-fish eggs, showing the young just emerging. 

 The latter coolly enter on their existence much in 

 the same shape as their parents, and immediately 



