422 DR. A. FARRE ON THE STRUCTURE OF THE CILIOBRACHIATE POLYPI. 
Fig. 5. X ISO. 
Fig. 6. X 180. 
Fig. 7. 
Fig. 8. 
Fig. 9 to 1 1. 
Fig. 9. 
Fig. 10. 
Fig. 1 1. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig. 16. a. 
b. 
The gizzard relaxed, with the dark bodies or constrictor muscles seen 
on opposite sides, and projecting into its cavity. The inner surface 
lined with teeth. 
The same in a state of contraction. The dark bodies elongated and 
brought into apposition, obliterating the cavity. (Both these figures 
as seen when the interior of the organ is in focus.) 
The gizzard torn open, and the teeth displayed. 
Portion of the pharynx, with the markings upon its surface. 
A series to show the mode in which the operculum and upper part of 
the body is unfolded. The same animal is represented in four dif- 
ferent stages. 
First stage. The top of the cell completely closed. The setae, folded 
up in the centre, 9 a, with the flexible portion of the cell b inverted 
and closely surrounding them. The muscles contracted, d d. 
Second stage. The bundle of setae a rising from the centre of the cell, 
being forced upward by the pressure of the tentacula. The flexible 
portion b rolling from around the setae, and the muscles d put upon 
the stretch. 
Third stage. The flexible portion b completely everted. The setae a 
still lying together. The tentacles just appearing between them. 
Fourth stage. The tentacula appearing above the margin of the oper- 
culum. The integument of the body, which forms the tentacular 
sheath half everted, c. The operculum completely expanded. The 
letters refer to the same parts in all. The last stage is seen in fig. 3. a. 
where the eversion of the integument is complete and the tentacula 
separated. (These stages are taken arbitrarily, the process being 
continuous.) 
The parietal muscles which assist in the act of protrusion. The knot 
is seen in the centre of each. 
Showing the position of the brown and white bodies. (Query, ova.) 
The same in a young animal. 
Two of these separated from the body. 
More highly magnified, showing the external membranous sac with 
contained granular matter. 
Plate XXII. p. 401. 
Vesicularia spinosa. 
Fig. 1 . X 3. A portion of the stem with the branches springing from its angles. 
Fig. 2. X 40. Small portion of a growing branch. The cells strictly unilateral, and 
