Fig. 17. A transverse section through the tips of the ampulla cells is here shown. To the left is towards the upper end of the ampulla. The basal bodies with the centrad fibers are in the plane of the section, while the flagella are supposed to extend below the plane of the section. ×1350. pp. 71. Fig. 18. These bodies, from within the ampulla cells, contain some of the secretion of the ampulla cells, and resemble the “floating bodies.” ×1350. pp. 72. Fig. 19. The “floating bodies” here represented are from the ampulla. Globules of a secretion similar to that found in the ampulla cells are seen both within and without the bodies. Note also the two black bodies without the cells and two or three similar ones within the cells. These latter bodies are of doubtful nature. ×1320. pp. 72. Fig. 20. This figure represents sections of the various nuclei found within the ampulla cells. ×1350. pp. 69, 70. Fig. 21. These cells are from the same preparation as Fig. 6. They are evidently retinal cells from the simple eyes. The tendency of their pigmented ends to become globular, I believe, is due to their having become isolated before they hardened during maceration. ×920. pp. 62. Fig. 22. This diagram illustrates the retraction of the long pigment cells. The dotted lines in the vitreous body mark the outlines of the prisms, while the continuous lines represent the axial fibers of the prism and pyramid cells. pp. 45, 46, 48, 49, 53. Fig. 23. These cells are from the epithelium of a sensory club. They are from the same preparation as Fig. 6. Flagella are not shown. ×900. p. 64. Fig. 24. This group of epithelial cells of a club are from the same preparation as Fig. 6. ×850. p. 64. Fig. 25. This sketch is a transverse section through the tips of the epithelial cells of a club. The polygonal areas are the cells, while the central dots are the centrad continuations (nerve fibers) the flagella of the cells. ×920. pp. 63, 65, 66. Fig. 26. The flagella of the epithelium of a club are in this figure seen to extend centrad, some beyond the nuclei. Cell outlines are not shown. ×920. pp. 64, 65, 66. Fig. 27. The cells of the lower half of this figure belong to the ampulla, those of the upper half to the canal of the peduncle. The right side of the figure is towards the eyes (the ventral side) of the club. Globules of secretion are seen within the ampulla cells, as also a globule without. The ring above the latter globule is probably an empty shell of a floating cell. ×1320. pp. 68, 69, 71, 73. Fig. 28. This figure is from a transverse section of a tentacle of Charybdea. The mass with darkly stained granules is the remains of a thread cell. The ectoderm and a small part of the supporting lamella only are figured. Note the large ganglion cell. ×920. pp. 74, 75.