EXPLANATION OF PLATE IX. 



FIGS. I2-l6. Salpa punctala, chain form. Compare Fig. 2. 



FIG. 12. Longitudinal vertical section of eye and ganglion. 



FIG. 13. Cross-section through the eye near the tip. 



FIG. 14. Cross-section through the middle of the eye. 



FlG. 15. Cross-section through the eye near the base. In a section still further 

 back the pigment would appear ventrally as well as laterally. 



FlG. 16. Horizontal section through the distal end of the duct of one neural gland, 

 showing convolutions at the aperture of the duct. 



FlG. 17. Longitudinal vertical section of the eye and ganglion of Thalia deino- 

 cratica-mucronala, chain form (copied from Metcalf). 



FlG. 18. Longitudinal vertical section of the eye and ganglion of Cyclosalpa fin- 

 nafa, chain form (copied from Metcalf). 



FIG. 19. Oblique (horizontal-cross) section through the middle of the eye of 

 Cyclosalpa chamissonis, chain form (copied from Metcalf). 



FIG. 20. Longitudinal vertical section of the eye and anterior part of the ganglion 

 of Salpa runcinata-fusifornris, chain form (copied from Metcalf). 



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