296 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



L.t.b.). These are extremely important structures, and 

 run back a considerable distance, to branch finally and 

 become attached to the floor of the proboscis. They will 

 be termed the Lateral odontophoral bands. These bands 

 form the meeting place at their anterior extremities for 

 a number of dorsal and ventral muscles and the odonto- 

 phoral cartilage. Thus many of the muscles of the 

 radula are not attached to the walls of the proboscis 

 directly, but to two lateral musculo-connective tissue 

 bands. Neither Geddes nor Oswald have figured this 

 muscle connection with the lateral bands correctly. 



The odontophoral cartilage is formed of two long 

 band-like lateral cartilages, which are much thicker at 

 their anterior ends and somewhat L-shaped in section. 

 They fuse ventrally at their anterior ends, and thus by 

 reason of their shape form the walls of a gutter or groove 

 open dorsally (figs. 20, 18 and 23). In addition, they 

 are united posteriorly by the sheet of transverse muscle 

 fibres, the companion structure to the dorsal sheet already 

 noticed (fig. 18, V.e.m.). 



Upon this odontophoral cartilage lies the radula. 

 There is usually about 20 mm. of it on the dorsal surface, 

 and 10 mm. on the ventral. 



The muscles of the odontophore may be divided 

 into : — 



I. Muscles attached to radula, (a) dorsally, and 

 (b) ventrally; 

 II. Muscles attached to odontophoral cartilage; 

 or 



I. Protractors, (a) of Pharynx, and (b) of 

 Radula and Cartilage. 

 II. Retractors, (a) dorsal, and (b) ventral. 



The protractors of the Pharynx consist of two 

 muscles which run dorsally from the anterior end of the 



