THE ANATOMY OF FLEUBOTOMARIA BEYRTCHII. 233 



into the extrinsic and the intrinsic muscles; the former 

 being concerned more in the movement of the mass as a 

 whole, while the latter are speciall}^ related to the movements 

 of the odontophore. 



Extrinsic Muscles. — Curiously enough, these seem to be 

 mainly protractor muscles, the retractors being but feebly 

 developed. 



(1) The lateral protractors. Three laterally placed 

 vertical sheets of muscle arising from the side wall of the 

 head, and inserted towards the posterior end of the buccal 

 mass (fig. 30 A, l.pr.). 



(2) The ventral protractors. A large paired muscle 

 arising from the region of the lower lip, and inserted upon 

 the basal cartilages (fig. 30 H, v.pr.). 



(3) The lateral retractors (? divaricators of the carti- 

 lages). Five or six small strands of muscles arising from the 

 side wall of the head, and inserted upon the main odonto- 

 phoral cartilage just below tlie edge of the radular membrane 

 (figs. 9 and 30 ^ Lr.). 



(4) The ventral retractors (?). A pair of short longi- 

 tudinal sheets of muscle arising from the body-wall just 

 above the pleuro-pedal cords, and inserted upon the radular 

 sac as it emerges from the odontophoral mass (figs. 29 and 

 30 A,v.r.). 



(5) The depressor muscle (figs. 30 £ and D, tZ. m.). A 

 small muscle inserted upon the main cartilage, just in front 

 of the insertion of No. 3, and passing down to the ventral 

 side of the head. 



I have called Nos. 3 and 4 retractors because when the 

 buccal mass is protruded their fibres would be on a stretch, 

 but I think that this is probably only part of their function. 

 Thus if the right and left portion of No. 3 contracted to- 

 gether they would separate the main odontophoral cartilages, 

 and No. 4 may also function to prevent too great a displace- 

 ment of the growing part of the radula. 



Intrinsic Muscles. — These, again, fall under two heads : 

 those concerned in the movements of the radula itself by 



