CEPHALOPODA. 



621 



eye-ball. These consist of three straiglit muscles and one oblique, 

 wliich take their origin from the orbital cartilages, and expand upon 

 the sclerotic tunic of the eye-ball. The cornea of the cuttle-fish is 

 perforated by a minute hole near the inner or anterior margin. In 

 the Octopus the corresponding aperture is somewhat larger, and 

 situate more in the axis of vision. In the Calaraaries the corneal 

 aperture is still larger, of a vertically oblong form, and the capsule of 

 the crystalline lens, which projects through the sclerotic aperture, is 

 immediately exposed to the sea water. 



The Dibranchiate Cephalopods are, without exception, predatory 

 and carnivorous animals. We have seen that they are endowed with 

 formidable organs for seizing and overcoming the struggles of a living- 

 prey, and their strong sharp hooked jaws are well adapted for de- 

 stroying and lacerating them when caught. The jaws {fig. 225, «, h ; 

 fig. 227, ^, /) are sheathed upon a firm fleshy substance (c), the fibres 



225 



Onyclioteathis. 



of which are so attached to the base of the mandibles as to open 

 them ; their closure is effected by fasciculi of muscular fibres which 

 surround them externally. 



The tongue is partially covered with a liorny plate (/), beset with 



