CHAM A. 77 



ciesj C. Gigas, which is the largest of all testace- 

 ous productions, and is sometimes as much as two 

 feet or more in breadth. The oval, or rather lan- 

 ceolate opening in the posterior slope, is probably 

 made use of by the fish to eject abyssus, with 

 which it fastens to rugged substances and resists 

 the action of the waves. 



The very incongruous varieties of external forms, 

 of surface^ and of general character, which distin- 

 guish the several species of the 2d section, render 

 it impossible to offer a good example in illustration 

 of the family ; it has not, therefore, been attempt- 

 ed. Although the margins in this division be not 

 all perfectly closed, yet they are comparatively so ; 

 and are obviously separated merely as a passage 

 for nutriment, not for any substance such as a 

 bunch of adhesive filaments. 



