DR. A. FARRE ON THE STRUCTURE OF THE CILIOBRACHIATE POLYPI. 421 
Description of the Plates*. 
The linear enlargement of each figure is expressed by the numbers with the sign x prefixed. 
ClLIOBRACHIATA. 
Plate XX. and XXI. fig. 1 to 16. p. 391. 
Bowerhanhia densa. 
Fig. 1 . a. 
h. 
Fig. 2. X 40. 
Fig. 3. X 80. a. 
b. 
c. 
d. 
Fig. 4. X 80. 
A specimen of the natural size, with the creeping stems closely set 
upon a piece of Flustra foliacea. 
A portion of the same separated. 
The same as fig. 1 . b. The animals are seen in various positions, and 
in all stages of growth. 
One of the animals fully expanded. 1. Pharynx. 2. Cardia. 3. Man- 
ducatory organ, or gizzard. 4. Stomach, its parietes studded with 
the hepatic follicles. 5. Pylorus. 6. Intestine, containing pellets 
of feculent matter. 7 - Anus. The gastric (8) and tentacular (9) 
retractors are seen within the cavity of the body. The flexible por- 
tion of the cell, or the operculum, is seen expanded and surrounding 
the upper part of the body. 
A similar animal completely retracted. The stomach drawn to the 
bottom of the cell. The upper portion of the alimentary canal flexed. 
The tentacula somewhat distorted by the pressure of the operculum. 
Their retractor filaments relaxed, 1 . The upper part of the cell is 
occupied by the operculum folded up in its axis, and from it the 
upper and lower sets of opercular retractors are seen radiating, and 
in their contracted state. 2 and 3. These filaments are about 
inch diameter in this state. 
An immature animal. The tentacula and alimentary canal rudely 
formed ; the cavity in the latter very distinct. The tentacular and 
opercular retractors also shown. 1. The gizzard. 
One of the gemmse in its earliest state. The cavity just defined, but 
no animal distinguishable. 
Portion of the alimentary canal, showing very distinctly the cardia. 
Gizzard with the dark points, radiating lines and teeth. Hepatic 
follicles and pylorus. 
* In the representation of specimens of the natural size, I have in most cases selected such small portions as 
may be just sufficient to afford a recognition of the species, to avoid encumbering the plates with points which 
are of minor importance, and which, moreover, would be unsuited to pages not devoted to zoological subjects. 
This remark is particularly applicable to the figure of Halodactylus , PI. XXV. 1 ., which conveys no idea of the 
size to which the aggregate masses sometimes attain. 
3 i 2 
