THE CARNIVOROUS Sl-UGS OF SOUTH AFRICA. 167 



Numerous muscles arise in two rows, one on each side of 

 the mid-dorsal line of the outer sheath of the odontophore, 

 and, passing' downwards outside the lateral retractors, are 

 attached to the outer sides of the support just below them 

 (PI. XYII, fig-s. 91, 104, and PI. XYIII, figs. 115-121). These 

 muscles I am terming the suspensor muscles of the support. 

 They are nowhere of any great thickness, but are decidedly 

 thinner behind than in front. 



A thin layer of ventral muscles arises from the hind end of 

 the odontophoi-al support, and is inserted in the anterior part 

 of the radula, or rather in the walls of the ventral pocket 

 which contains it (PI. XVII, figs. 91, 92, 101, 104, and PI. 

 XVIII, figs. 117-121). These muscles do not only run longi- 

 tudinally beneath the centre of the support, but the more 

 lateral strands diverge radially from the ventral pocket of the 

 radula and unite with the suspensor muscles of the support 

 on each side. They serve to pull back the anterior part of 

 the radula over the fi-ont edge of the support, and thus to 

 pull forward the radula-sac when its retractors are relaxed, 

 so that the radula assumes the form shown in PI. XVII, figs. 

 92, 97, 102, 1 14. Then, when the teeth have become imbedded 

 in the skin of the prey, these ventral muscles will be relaxed, 

 and the powerful retractors will draw back the radula until 

 it has the form shown in fig. 98. 



A slender median dorsal muscle is inserted in the sheath of 

 the odontophore, between the suspensor muscles, a short 

 distance behind the opening of the oesophagus, and is 

 attached posteriorly to the front end of the terminal 

 retractors, its sides also becoming connected with the neigh- 

 bouring lateral retractors (PI. XVII, fig. 92, and PL XVIII, 

 figs. 116-120) . This is evidently homologous with the muscle 

 that Amaudrut terms the "papillaire superieur." It 

 may assist the ventral muscle in pulling forward the radula- 

 sac, but its chief function is probably to pull back the 

 posterior lip of the opening of the oesophagus when the 

 retractor muscles are brought into play, thus making a wide 

 passage towards the crop. 



