REPOKT OX THE TUNICATA. 
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conspicuous object (PL XIY. fig. 22, v.cl.). It brancbes tbrougli the genital mass, giving 
ofi" a tvfig to each spermatic vesicle, and on leaving the mass at its anterior end attaches 
itself to the rectum, along which it runs anteriorly to open into the peribranchial 
cavity. 
Tailed larvae were found in some of the Ascidiozooids ; they have ovate bodies with 
conspicuous sense organs placed far back (PL XIV. fig. 23). 
Polyclinum depressum, n. sp. (PL XXVI. figs. 5-7). 
Tlie Colony is an irregularly discoid mass incrusted with stones and shell-fragments. 
The upper free surface is flattened, while the lower attached part is rather convex. The 
surface is very irregular, and not smooth. The colour is fight grey. 
The length of the colony from the base of attachment to the free surface is 1'5 cm., 
the greatest breadth is 5 cm., and the greatest thickness 4 cm. 
The Ascidiozooids are fairly large, but few in number, and very irregularly scattered. 
They are usually about 5 mm. in antero-posterior length, and are distinctly composed of 
two parts, the anterior consisting of the thorax and abdomen, and the posterior of the 
long post-abdomen. 
The Test is thick, but soft and gelatinous. It is of a fight grey colour and is semi- 
transparent. The matrix is clear and structureless, and contains numerous test cells, 
most of which are more or less rounded in form. No bladder cells are present. 
JJie Mantle is strong and opaque. The chief muscle bands run longitudinally and 
form over the greater part of the body a continuous muscular coating. The musculature 
on the post-abdomen is especially strong. 
The Branchial Sac is of small size. The stigmata are minute and inconspicuous. 
The Alimentary Canal is small, and the intestine forms a narrow loop. 
The Post-Ahdomen is very large. It springs from the ventral edge of the posterior 
end of the abdomen. 
Locality. — Torres Strait, north of Australia ; depth, 3 to 1 1 fathoms. 
This species is formed for a flat incrusting colony obtained in Torres Strait, between 
Australia and New Guinea, from a depth of 3 to 11 fathoms. It has evidently been 
attached by more than half its surface to small stones, shell-fragments, and other foreign 
bodies, while a considerable portion of even the upper surface is incrusted with Polyzoa 
and Zoophytes. Where exposed the surface is irregular and roughened (PL XXVI. fig. 5). 
It does not vary in colour, being a fight grey all over. No common cloacal apertures 
and no systems of Ascidiozooids are visible in any part of the colony. 
The Ascidiozooids are of an opaque pale yellow colour, and seem to be placed very 
irregularly in the test ; they fie at all angles to the outer surface. The abdomen is not 
(ZOOL. CHALL. EXP. — PAET XXXVIII. — 1885.) Pp 25 
