EEPOET ON THE TXJNICATA. 
231 
Amaroucium Imvigatum, n. sp. (PL XXX. figs. 12-15). 
The Colomj is of an irregular ellipsoidal form and is unattaclied. All its surfaces are 
rounded, and there is slight lateral compression. The colour is pale dull yellow. The 
surface is even and is fairly smooth all over. 
The length is 3 cm., the breadth 2 cm., and the greatest thickness 1‘8 cm. 
The Ascicliozooids are very small and rather numerous. They are narrow, and 
the post-abdomen is elongated to form a narrow filament running towards the centre 
of the colony. The arrangement of the Ascidiozooids is irregular. 
The Test is firm and solid and almost perfectly opaque. The matrix is clear and 
homogeneous, but it is crowded with test cells of various sizes and shapes. Many of 
them are of rounded form and rather large size, and are darkly coloured, others are 
smaller and are elongated and fusiform. There are no bladder cells. 
The Mantle is moderately strong. The muscle bands are not numerous, and they run 
mainly in a longitudinal direction. They are distant on the thorax and feebly developed 
on the abdomen, but become more closely placed on the post-abdomen. The branchial 
aperture is six-lobed. 
The Branchial Sac is long and narrow. The transverse vessels are rather wide and 
are all of one size. The stigmata are well developed and numerous. They vary some- 
what in size. 
The Tentacles are large, and are all of about the same size. 
The Alimentary Canal forms a long narrow loop. The stomach is small, but has its 
wall folded longitudinally. 
Locality . — Station 313, January 20, 1876; lat. 52° 20' S., long. 67° 39' W.; depth 
55 fathoms; bottom, sand; bottom temperature, 47°'8 F. 
The single specimen of this species was obtained at the eastern end of the Strait 
of Magellan, from a depth of 55 fathoms. It is a small compact colony which apparently 
was not attached by any part of its surface (PL XXX. fig. 12). Ascidiozooids are seen 
all over the colony, which probably lay on the sand, since dark sand-grains are found 
imbedded in the test at one of the ends (PL XXX. fig. 12). In cross section the 
shape of the specimen is triangular, with rounded angles and depressions on the sides. 
These depressions, however, are possibly the result of contraction on being put into 
alcohol. The colour is more of a pale yellow than a grey. At one end it is darker on 
account of the imbedded sand-grains. 
The anterior ends of the Ascidiozooids may be seen all over the surface as very faint 
pale yellow spots (PL XXX. fig. 12). Nothing further can be made out on account of 
the opacity of the test. In some places the Ascidiozooids seem to be arranged in small 
circular systems, but elsewhere they are scattered quite irregularly. 
The test is cartilaginous in consistence, and is hard and firm throughout the whole 
