EEPORT ON THE TUNICATA. 
'297 
The Asoidiozooids, although of fair size, are iu most places not visible on the exterior 
of the colony (PI. XLI. fig. 1, B.), hut in a few spots they can be made out as small 
white rounded areas. The body as a whole is elongated antero-posteriorly, and is placed 
at right angles to the surface (PI. XLI. fig. 2). The abdomen is rather larger than 
the thorax. 
The test is relatively large in amount, and is remarkably soft and flexible for a 
Leptoclinid. The test cells are very numerons, and are mostly of small size and of 
rounded or fusiform shapes ; here and there, however, larger test cells of stellate and 
branched forms occur (PI. XLI. fig. 3, t.c.). 
The spicules are much less numerous than in most species of Leptoclinuin (PI. XLI. 
figs. 2, 3). Some of them are twice or even three times as large as others, but they are 
all stellate in form, and their rays are regular and pointed at the apices (PI. XLI. fig. 3, sp.). 
A vertical section through the colony (see PI. XLI. fig. 2), shows that the spicules are not 
equally scattered all through the test, but are most abundant immediately around the 
anterior ends of the Ascidiozooids. At this level the spicules form a continuous dense band 
stretching throughout the section, becoming- thickened in the neighbourhood of each 
Ascidiozooid and thinning out in the intermediate regions. Above this band the super- 
ficial layer of test, as we have already seen, contains no spicules (PI. XLI. fig. 2, t.m .) ; 
while below, in the deeper parts of the colony, spicules are present, but they are scattered 
sparsely and evenly through the test. 
Eetractor muscle bands and ectodermal processes from the Ascidiozooids are also met 
with in the te.st (PL XLI. figs. 2, 3, m.h., v.). The hitter are given off from the 
oesophageal region of the body where the thorax and the abdomen join, and they run 
mainly in a posterior direction, towards the centre of the colony. They are not very 
long and do not give off any branches. Their ends are rounded and slightly dilated 
(PI. XLI. fig. 3, V.). 
The branchial siphon is lined by test which contains spicules (PI. XLI. fig. 2). 
The sphincter surrounding it is well marked. The endostyle is large and conspicuous. 
The branchial sac is remarkably wide dorso-ventrally, usually it is as wide as or wider 
than its antero-posterior length. The stigmata are well formed (PI. XLI. fig. 4), and 
the muscle bands in the transverse vessels are unusually strong. In one of tlie 
Ascidiozooids shown in the section (PI. XLI. fig. 2), only three rows of stigmata were 
visible in the branchial sac. The posterior end of the branchial sac is very wide and flat, 
and it is from this region, between the posterior extremity of the endostyle and the 
oesophageal opening, that the ectodermal processes or vessels arise (PI. XLI. fig. 2). 
The oesophagus commences at the dorsal edge of the posterior end of the branchial sac 
and runs straight backwards for a short distance to open into the short, and, in some 
cases, almost cubical stomach (see PI. XLI. fig. 2). There is a certain amount of vari- 
ability in the form of the stomach even in Ascidiozooids of the same colony. The 
(ZOOL. CHALL. EXP. — PART XXXVIII. 1886.) Pp 38 
