THE NATURAL HISTORY SURVEY. 41 
this report, a brief discussion of the seweral parts of the teeth is 
here presented. 
The buccal-body is placed either at the end of a rostrum or 
in the body of the head; in the former it is nonretractile. The 
PoLyGYRA ALBOLABRIS, showing parts of animal. (After Binney, L. and 
F-W, Sh., fig. 280.) e, eye; ep. eye-peduncles; f, foot; h, head; n, neck; sh, 
shell; t, tentacles. 
odontophore (or radula) is formed in the radula sac (Fig. 7, 18), 
where it is pushed forward as needed. Anteriorly the ventral 
portion of the pharynx forms a stout cartilage (5) which is pro- 
vided with protractor (6) and retractor (7) muscles, by which 
the cartilage is moved backward and forward. The radula 
————> tH 
Re ee 
Buccal organs of Hexix (Guides for Science Teaching, Bost. Soc. Nat. 
Hist., VI., fig. 26). 1, cesophagus; 2, radula; 3, core of radula; 4, new 
teeth forming; 5, cartilaginous substance beneath the radula, serving for sup- 
port and for the attachment of muscles; 6, posterior cartilage muscles; 
7, anterior cartilage muscles; 8, cartilage bearing jaw; 9, jaw; 10, outer 
surface of mouth; 11, upper lip; 12, lower lip; 18, under surface of lip; 
14, orifice of mucous glands; 15, mucous glands; 16, mouth; 17, cells 
lining under surface of radula; 18, radula sac. 
(2) rests upon this cartilage, being strongly fastened at the an- 
terior end, and is brought down between the two fleshy lips 
(11, 12) and there exerts a backward and forward movement, - 
rasping off with its sharp teeth particles of food as they are 
