OF THE ODONTOPHOEE IN CBETAIN MOLLUSCA. 489 



In conclusion I have only to express my warmest thanks to Professor Huxley for 

 suggesting, encouraging, and supplying the materials for the above inquiry. 



EXPLANATION OF THE PLATES. 

 PLATE LXXX. 



Figs. 1 to 9. Odontophore oi LoUgo, sp., natural size. 



Fig. 1 . Left side : t, the soft spongy " taste-organ " with its muscles ; r, the radula ; /, 

 old half dissolved portion ; irs, infraradular sheet ; edbn, its single median ex- 

 ternal dorsal longitudinal muscle ; vis, its left ventral longitudinal muscle ; c, 

 the anterior so-called " cartilage ; " vtf, ventral transverse fibres connecting 

 the cartilages ; el, external longitudinal muscle of left cartilage ; g, the gullet. 



Fig. 2. Taste-organ and gullet removed. 



Fig. 3. External longitudinal muscle of left cartilage removed, showing dtf, dorsal 

 transverse fibres uniting cartilages, c. 



Fig. 4. Eadula half pulled out, left ventral muscle of infraradular sheath cut away ; 

 dtf and vtf, dorsal and ventral transverse fibres of cartilages cut across, 

 showing rs, sheath of radula, and dim, dorsal longitudinal muscles. 



Fig. 5. Median longitudinal vertical section completed^ 



Fig. 6. Dorsal aspect, edlni partly cut away. 



Fig. 7. edhn entirely cut away ; dtf cut open, to expose dorsal longitudinal muscles of 

 infraradular sheet ; radula half pulled out. 



Fig. 8. Ventral aspect, showing irs with its muscles, vis ; also the cartilages c, and their 

 ventral transverse fibres vtf. 



Fig. 9. Median transverse vertical section. 



Figs. 10 to 23. Buccal mass oi Patella vulgata, x 3. 



Fig. 10. Dorsal surface : pr, antero-lateral and postero-lateral protractors ; ;•, radula 



ms, muscles of infraradular sheet. 

 Fig. 11. Kadula removed; irs, infraradular sheet ; ms, its muscles. 

 Fig. 12. Infraradular sheet and muscles removed, showing cartilages with their muscles ; 



ac, anterior cartilage ; j)c, posterior cartilage ; Ic, lateral cartilage ; aim, muscle 



uniting anterior and lateral cartilages. 

 Fig. 13. aim removed, showing cartilaginous framework ; vtr, ventral transverse fibres 



of anterior cartilages. 



' See also Bronn's ' Thier-Eeich,' Malacozoa, plate cxvi. 



