MR. P. GEDDES ON THE MECHANISM 
. Ventral aspect of buccal mass: /, lips; j, horny jaw; vpr, sheet of ventral 
protractor fibres. 
5. Ventral protractors removed: v/s, ventral longitudinal muscles of infraradular 
sheet ; vtr, ventral transverse fibres; v'ti’, inner ventral transverse fibres. 
. Radula turned forward: infraradular sheet and its muscles shown. 
. Infraradular sheet cut away ; 77s, its cut edge; ac, the slightly inrolled apex 
of anterior cartilages. 
. Transverse muscles all cut away, leaving framework ; vfr and v'tr’, their cut 
edges. 
. Cross section of framework towards apex, showing deep sulcus. 
PLATE LXXXI. 
. Left side of buccal mass in situ: f, foot; 7, lips; 7, jaw; s, skin of head; 
vp, ventral protractor ; dpr, lateral protractor; g, gullet. 
Superficial muscles removed, showing left of framework. 
. Deep dissection, lateral cartilage removed; irs, cut edge of infraradular 
sheet. 
3. Left anterior and posterior cartilages removed, thus completing median 
longitudinal vertical section. 
Figs. 24 to 34. Buccal mass of Buccinum, (24-81, x3; 32-34, x 6.) 
. Skin laid back, dorsal aspect ; 7, radula, seen through window cut in gullet, 7 ; 
mg, small muscles which attach gullet to skin ; dtf, dorsal transverse fibres 
sheathing upper part of apparatus ; murs, muscle of radular sheath ; d/m, other 
dorsal longitudinal muscles. 
. Gullet removed, showing e¢pr, circular protractor of lips, and lpr, lateral 
protractors. 
. Dorsal transverse fibres laid back, showing mode of attachment of radular and 
underlying sheet; c, the cartilages, their edges thickened by muscles; rs, 
radular sheath, whence pass slips of muscle to cartilages; d/m, the complex 
dorsal longitudinal muscles. 
. Radular sheath and muscles, all cut save the deepest set, dim’; v/s, ventral 
longitudinal muscles. 
PLATE LXXXII. 
. Ventral aspect, showing lower attachment of radula ventrally: v/s, ventral 
longitudinal muscles ; vt, ventral transverse fibres ; g, depression leading into 
gullet. 
