PLATE II.

Fig. 5.-Leucosolenia cancellata (page 27). Twice the natural size.
Fig. 5a. Vertical section through the specimen figured; X 6.
Fig. 5b. Part of the same section; X 42.

Figs. 5c, 5d. Gastral quadriradiate spicules; X 272.

Fig. 5e. Triradiate spicule; × 272.

Fig. 6.-Sycon Eglintonensis (page 29). Twice the natural size.
Fig. 6a. Part of a horizontal section; X 60.
Fig. 6b. Gastral quadriradiate spicule; X 272.
Fig. 6c. Gastral triradiate spicule; X 272.
Fig. 6d. Tubar triradiate spicule; X 272.
Fig. 6e. Large oxeote spicule; X 136.

PLATE III.

Fig. 7.-Sycon mundulum (page 28). Twice the natural size.
Fig. 7a. Part of a horizontal section; X 136.
Fig. 76. Gastral quadriradiate spicule; X 272.
Fig. 7c. Gastral triradiate spicule; X 272.
Fig. 7d. Tubar triradiate spicule; X 272.
Fig. 7e. Oxeote spicule; X 136.

Fig. 8.-Amphoriscus Thompsoni (page 36).

Twice the natural size.

Fig. 8a. Part of a horizontal section; X 136.
Figs. 8b, 8c. Gastral quadriradiate spicules; × 272.

Fig. 8d. Gastral triradiate spicule; X 272.

Fig. 8e. Subgastral triradiate spicule; X 272.

Figs. 8f, 8g. Subdermal triradiate spicules; X 272.

Fig. 8h. Dermal triradiate spicule; X 272.

Fig. 8i. Stout oxeote spicule; X 272.

Fig. 8. Linear spicule; X 272.

PLATE IV.

Fig. 9.-Grantia Phillipsii (page 30). Twice the natural size.
Fig. 9a. Part of a horizontal section; X 136.
Fig. 96. Gastral quadriradiate spicule; × 272.
Fig. 9c. Tubar triradiate spicule; X 272.

Figs. 9d-g. Dermal triradiate spicules; X 272.

Fig. 9h. Triradiate spicule of the stem; × 272.
Fig. 9i. Oxeote spicule; × 272.

Fig. 10.-Leucandra valida (page 32). Twice the natural size.
Fig. 10a. Part of a horizontal section; × 60.

Figs. 10b-e. Triradiate spicules of the parenchyma; X 136.