26 
ZOOLOGY OF THE FAR EAvST. 
Lateral branches are usuall}^ given oft in the neighbourhood of groups of zooecia, but 
the tips of these branches divide dichotomousl}^ in front of the last zooecium (pi. i, 
fig- 10). 
The size of individual zooecia varies greatly both in the same colony and in colo- 
nies from different localities or growing under different conditions. If the organism 
is threatened by the deposition of mud in its interstices^ as often happens if it is 
attached to the roots of reeds in muddy estuarine waters, some zooecia are often of 
very great length without attaining more than normal girth. The following table 
gives, in millemetres, the length and greatest transverse diameter in the longest 
zooecium discoverable in four colonies from different localities, the first two of which 
are situated on different sides of the Malay Peninsula, while the two latter are in the 
Gangetic delta : — 
Port Weld. Tale Sap. Calcutta. Port Canning. 
Length . . 178 1-02 2 55 0775 
Breadth . . . . 0-204 0-119 0'255 Q-iig 
The zooecia are always more or less spindle-shaped, tapering both above and at 
the base, which is usually prolonged below the point of attachment to the rhizome in 
the form of a pointed process or " tail." If this tail comes in contact with a hard 
object it is often expanded into a funnel-like body, concave at the tip, which attaches 
itself to the object. Its position is sometimes a little eccentric so that it is situated 
at one side of rather than in the middle line of the main body of the zooecium, the 
base of which then grows out into a lateral pocket, thus giving the whole structure a 
bifid appearance (text-fig. 4, A) ; but the tail never forms a branching radicle. The 
distal region of the zooecium is subcircular in cross-section. Its ectocyst is faintly 
and minutely striated transversely, but the striae are often obsolete. The tint of the 
ectocyst varies greatly ; often it is colourless but sometimes it is stained with yellow 
or brown. It is always transparent. 
In both arrangement and number the parietal muscles vary considerably. Some- 
times they are practically confined to the upper part of the zooecia, while in some 
zooecia they extend almost to the base (c/. figs. 10 and 10a, pi. i). 
There are always 8 tentacles, which are armed with a sensory bristle at the base, 
with several horizontal hairs on the outer margin and a bunch of finer hairs at the 
tip. The alimentary canal resembles that of other species. The diameter of the giz- 
zard varies with the size of the zooecium (c/. pi. i, figs. 10, loa and 11) 
B. caudata, therefore, differs from the form described by Waters ^ and by Harmer ^ 
as B. imhricaia in the following characters : — 
(1) The zooecia are more slender and less cylindrical; their base never forms a 
binding radicle. 
(2) They are joined to the rhizome by a distinctly lateral communication and 
never exhibit any approach to a spiral arrangement. 
1 Journ. Lin. Soc. XXXI, p. 248, pi. xxv, figs 6-10 (1910). 
2 Siboga-Exp., mon. XXVIIIa, p. 70, pi. vii, figs. 15, 16 (1915). 
