PLATE 2. 



Fig. 7. Portion of cross section of proboscis, showing structure of lemniscus. 

 Sea-water and alcohol, vom Path's mixture. X 200. 



Fig. 8. Part of Fig. 7 enlarged. X ca. 400. 



Figs. 9a, 96. Sections of a papilla perpendicular to its axis. Figure 9a represents 

 the more distal of the two sections, and shows the form and position of the 

 three axial nuclei ; Figure 96 shows the two basal nuclei. The anterior face 

 of the papilla is directed toward the top of the plate in both cases. 

 Sea-water and alcohol, corrosive sublimate, iron haematoxylin. 



Fig. 10. Portion of the cross section of an everted proboscis, showing one of the 

 eighteen longitudinal nerves (n. Ig.) cut crosswise, the peripheral nerve plexus, 

 the union of the centripetal processes from the sense cells with the longitudinal 

 nerve (in the case of the third papilla from the upper margin of the Figure, 

 one of the two nerve fibres bends to the left when it enters the nerve plexus, the 

 other to the right), a radial nerve (n. r.) following the surface of the longitu- 

 dinal muscle (this is sketched in from an adjacent section), and another radial 

 nerve (n. r.') passing directly to the membrane which is immediately superficial 

 to the circular muscles. 



Chloroform, methylen blue, Bethe's ammonium molybdate for invertebrates. 

 X 145. 



Fig. 11. Papilla from a cross section of proboscis showing one of the basal and 

 one of the axial nuclei ; there are two large granulations in the basal nucleus. 

 The differentiation of the distal portion of the sense-cell is not well shown. 

 Sea-water and alcohol, sublimate-acetic, Kleinenberg's haematoxylin. X 460. 



