720 



THE AMERICAN NATURALIST [Vol. XL 



Odontophoral (Buccal) Cartilj 



The radula or dentated ribbon is essentially a thin flexible file 

 vhich is worked back and forth over the odontophoral cartilage. 



Bv the protraction or retraction of 

 this cartilage over which the radula 

 runs like a strap over a pulley, the 

 lingual file (or better, rasp) is either 

 brought forward into the mouth to 

 a position where, aided by the hard 

 hps, rasping can be effected, or (on 



ihe cartilage has two long rawt 

 that unite anteriorlv to form a head 

 (Fig. 8), the entire length being from 

 five to six centimeters m a fair-sized 

 specimen, ihe cartilage has some- 

 what the form of a toboggan that has 

 been split up along the running part 

 toneartlH'ui.turncdfn.nt: tl.c front 



forward on the dorsal, 

 rather posterior surface 

 the upturned he 

 these grooves that the 

 ribbon itself passes ovi 



Iti. 1 



h( ul <,t ih, ( urili 



