PLATE 1. 



Fig. 1. Longitudinal section of the everted jjroboscis showing: (1) the sheatli of 

 the proboscis; (2) the bearer of the jaws and its sulidivision ; and (3) the 

 lemniscus {tinn.), wliich marks the boundary between (1) and (2). 



Narcotized in a mixture of sea-water and alcohol; fixed in Miiller's fluid; 

 stained witli Beale's ammonia carmine. X circa 11. 



Fig. 2. Cross section of the partial!}' everted proboscis in the region of tlie four 

 lemnisci {Imn.), sliowing, among other things, a diagrammatic representation 

 of the papillae and the connection of their sensory cells with tlie circular and 

 tlie longitudinal nerves, and also the nerve fibre (n. r.') passing to the membrane 

 which invests the circular muscles. 



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

 X 14.5. 



Fig. 3. Papilla from a cross section of the proboscis, showing two "basal" and 

 three "axial" cell nuclei. 



Sea-water and alcohol, sublimate-acetic, Kleinenberg's haematoxylin. X 675. 



Fig. 4. Longitudinal section of a papilla, from a cross section of tlie proboscis, 

 showing the two axial nuclei and one of the two basal nuclei, also fibrous struc- 

 tures entering the base of the papilla. Treatment the same as in Fig. 3. 

 X 585. 



Fig. 5. Longitudinal section of a papilla, from a sagittal section of the proboscis, 

 showing two sensory axial cells with peripheral sensory termination and 

 prolongation of the basal end of each into a slender nerve fibre. 



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

 X 050. 



Fjg. 6. Papilla from cross section of proboscis viewed from behind, showing the 



corrugations of the cuticula on the posterior face of the papilla, and in optical 



section the two zones of living substance togetlier with one of the basal nuclei. 



Sea-water aud alcohol, sublimate-acetic, Kleinenberg's haematoxylin. X 5b5. 



