DR. A. FARRE ON THE STRUCTURE OF THE CIUIOBRACHIATE POLYPI. 425 
Plate XXV. and XXVI. p. 405. 
Halodactylus diaphanus. 
Fig. ]. A small specimen of the natural size. The animals seen protruding 
from its surface. 
Fig. 2. X 40. The appearance presented by a lateral view of the surface. The ani- 
mals in various stages of protrusion. Their diameter doubled. 
Fig. 3. X 40. Thin transverse section of fig. 1. The centre occupied by a cellular 
tissue and water. The circumference formed by the cells in close 
apposition. The brown bodies scattered through the substance. 
a. a. Position of the gemmules, enclosed in the sac. 
b. One of the gemmules escaped during the section into the central 
tissue. 
Fig. 4. X 80. Thin slice from the surface, with a terminal view of the cells, showing 
their mode of arrangement, and various stages of growth. 
Fig. 5. x 80. A similar slice from a specimen which afforded a lateral view of the 
cells, as in Flustra. The muscles and granules distinct in both 
figures. 
Fig. 6. x 80. A young animal extracted, rudely formed. The cavities in the ali- 
mentary canal and arms are very distinct. 
Fig. 7- X 80. Group of animals. ( Lateral view of the surface as in fig. 2.) 
a. Fully expanded. The arrows mark the direction of the particles of 
carmine, in the currents produced by the ciliated arms. 
b. The arms turned over the margin of the cell as if to feel, preparatory 
to the entire protrusion of the animal. 
c. Animal nearly retracted. 
d. Empty cell. 
Fig. 8. Pharynx, with portion of tentacula. 
a. Pharyngeal line. 
b. Cardia. 
d. Constricted portion of pharynx ; above are seen the tubes in the arms 
and the apertures at their base. 
Fig. 9. The pharynx, with squamiform spots, triangular space, c. and dark 
line, a. 
Fig. 10. Appearance of a circumferential vessel in the tentacular ring. 
Fig. 11 to 16. A series illustrating the act of protrusion at different stages; at a. 
figs. 14, 15 and 16 is a circular band within the setse, apparently for 
the purpose of bringing them together, seen contracted at a 13. 
b 15. Integument half inverted, forming tentacular sheath. 
Fig. 16. b. Flask-shaped body. Lateral view. The arrow denotes the course 
of the ciliary motion. This specimen shows the oblique termination 
of the tentacula. 
