No. 478] ODONTOPRORM. M'J'AHATI S L\ sycdTYl'CS 729 



attention here, smce theiv purpose is to Keep tne reiracior true i 

 its grooved path. It sliould be stated in tlie first place that a cor 

 si(leral)le portion of the ra.hihir sac [)rojcets free above the root 

 of tlie retractor of the ra(kda, and is continued posteriorly into 

 rather long radular muficle that is inserted into the muscle cup f 

 the base of the proboscis (Fig. 11, rs., 

 rms.). The more anterior |:)art of tlie 

 radular sac has inserted into it laterally 

 and dorsally strands of muscle, some 

 of which pass forward to be inserted 

 into the outer edges of the rami of 

 the odontophoral cartilage; others pass 

 backward to the same edges, thus giv- 

 ing rise to a criss-crossing which serves 

 to keep the radular sac in position and 

 to prevent the great retractor leaving 

 its grooved pathway (Fig. 15). 



Dorsal to this double set of muscle 

 strands, i. c, more superficial, lies 

 what mav be called the dorsal sheet of 

 cro99 /hers (tigs 0, 11, dsef ),\\hkh 

 pass from the outer edffe of one ramus 

 to the outer edge of the other, not, how- 

 ever, along the entire length of the 



Ihe eml 'ilu^ (l.>i-il .lu . t uneis the 



part of the 



i> tlu 



All that 1^ 

 upon oi)eni 



