REPORT ON THE TIJNICATA. 
191 
The Dorsal Tubercle is a rounded opening placed near the base of the tentacles. 
The neural duct is very large. There is no peritubercular area. 
The Reproductive Organs are large ; they are hermaphrodite. 
Locality . — Port Jackson, Australia; depth, 6 to 15 fathoms. 
This is an interesting species. From its external appearance and its essential structure, 
it belongs to the Polyclinidse, but from some points in its internal anatomy it seems 
allied to ColeUa and the other Distomidse. There is only one specimen in the collection. 
It was obtained at Port Jackson, Australia, from a depth of 6 to 15 fathoms. 
In shape the colony is somewhat like a Fungus, being an irregularly discoid mass, 
flat below and rounded above (see PI. XIV. fig. 16). From near the middle of the 
lower surface there projects a mass of mud, &c., from 1 cm. to 1‘5 cm. in diameter, which 
indicates the point of attachment of the colony. This spot is seen in the side view 
(PL XIV. fig. 16) and still better in the vertical section (PI. XIV. fig. 17). The rounded 
upper surface (PI. XIV. fig. 15) rises from the edge on aU sides, but the slope varies, as 
may be seen by comparing the edges in figures 16 and 17. The edge nearly all round 
is thickened and slightly upturned (PI. XIV. fig. 17). The upper surface is covered 
all over with small rounded areas like flattened papillse (PI. XIV. figs. 15, 16). 
These are the anterior ends of the Ascidiozooids. They seem to be arranged quite 
irregularly, and are incrusted like the rest of the surface with adhering sand- 
grains. A vertical section through the colony (PI. XIV. fig. 17) shows that the 
Ascidiozooids are placed very closely side by side and reduce the test to narrow 
bars and membranes. They are all placed vertically, and they vary greatly in size, 
those in the centre — the highest part of the colony — being fully 8 mm. in length, 
while those at the edge measure only 4 mm. 
The opaque dull grey colour of the colony is due in great part to the surface layer of 
sand, the test below being of a much lighter grey and fairly transparent. There is really 
comparatively little test in this colony, the greater part of the mass being formed by 
the bodies of the Ascidiozooids. The test cells are notable on account of the absence of 
the long delicate processes so common in most other Ascidians ; here they are nearly all 
rounded or ovate in form. 
The mantle has regularly arranged transverse muscle bands which encircle the 
branchial part of the body, and a few smaller irregularly running bundles. The branchial 
siphon is small, and is distinctly six-lobed at its free end. 
The branchial sac is exceedingly long and narrow. It extends along the greater part 
of the body of the Ascidiozooid. There are in the mature sac ten or twelve rows of 
stigmata upon each side, and each row contains about twelve stigmata. The transverse 
vessels are not narrow (PI. XIV. fig. 18, tr.). The stigmata are arranged with great 
regularity, and are long with rounded ends. The ciliated cells are broad and low. 
