MOLLUSC A. 125 



stance of the tongue, expedite the progress of the food into 

 the gullet. 



The salivary glands are four in number, and are placed in 

 pairs. The glands of the first pair, seated on each side of the 

 muscular bed of the mouth, are divided into numerous lobes, 

 the excretory ducts of which pour their fluid into the beginning 

 of the gullet. The second pair, seated lower down and be- 

 low the eyes, are not so much divided, and send out separ- 

 ate canals, which unite and pour their contents into the 

 mouth. 



The gullet is furnished with a lateral expansion, not un- 

 like the crop of gallinaceous birds. The stomach is mus- 

 cular, like the gizzard of fowls, and the cuticle is thick, and 

 separates easily from the other membranes. At the pyloric 

 opening of the stomach, there is another aperture equally 

 large, which leads into the spiral stomach, or caecum, as it 

 has been improperly termed by some anatomists. It may 

 with greater propriety be denominated the duodenum, as it 

 performs some of the offices of that part of the gut in the 

 higher orders of animals. This stomach is conical, closed 

 at the distal extremity, and performs about a turn and a 

 half, like a spiral shelL Its inner surface is covered with a 

 ridge, which traverses it in a closely spiral direction. The 

 bile flows into it near the apex, and towards its base glan- 

 dular orifices, pouring out a thick, yellow fluid, may be ob- 

 served. The intestine, after leaving the pylorus, in some 

 species, makes one or two turns, in others, it proceeds di- 

 rectly to the anus. This opening is seated at the base of 

 the funnel, on its posterior or dorsal side. 



The liver is of considerable size, of an orange-yellow co- 

 lour, and of a soft and spongy texture. It gives rise to two 



