MOLLUSCA 
199 
The mouth leads into the cavity of the buccal mass, this 
is partially obliterated by the developement of a large ventral 
5). 
6. 
Uc 
cS 
1. Head. 8. 
2. Tentacle. 
3. Mantle skirt. 9. 
4. Muscles forming root of foot, and 10. 
adherent to the shell. ale 
Fic. 119.—Side view of anterior end of Limpet, 
Patella vulgata. Part of the mantle is cut 
away to show the contents of the pallial cham- 
ber. After Lankester—Zoological Articles re- 
printed from the Encyclopedia Britannica. 
Small nephridium. 
Large nephridium. 
External opening of small] ne- 
phridium. 
External opening of large ne- 
phridium. 
Anus. 
Rudimentary ctenidium. 
Pericardium. 
mass, over which the tooth-ribbon or radula works. The 
ventral mass contains certain cartilaginous nodules, and is very 
i} 
' 
’ 
! 
9 
Fia. 120.—Vertical section through the neck of Patella vulgata. 
After R. J. Harvey Gibson. 
Mouth. 
Buccal cavity. 
Palatal tooth. 
Radula. 
Odontophore. 
OUR oo No 
Anterior cartilage. 
Oesophagus. 
Radula sac. 
Foot. 
Ose ice 
muscular. The radula, which runs over it, is continued into a 
sac, from the blind end of which it grows (Fig. 120). The radula 
