KEPORT ON THE THNICATA. 
195 
The Branchial Sac is not large. Its wall is thick and opaque, and considerably 
corrugated. The stigmata are small and inconspicuous. 
The Alimentary Canal is large and quite opaque. The stomach is globular, and 
smooth walled. 
The Post- Abdomen is moderately long, and very irregular in its thickness. It is 
separated from the abdomen by a marked constriction. 
Locality. — Station 320, February 14, 1876 ; lat. 37° 17' S., long. 53° 52' W. ; depth, 
600 fathoms; bottom, green sand; bottom temperature, 37°'2 F. 
One specimen of this species was obtained by the trawl off the east coast of South 
America at a depth of 600 fathoms. It is a dull grey-coloured soft-looking colony 
attached by a wide base to a mass of sand and fragments of Polyzoa and other foreign 
bodies (PL XXV. fig. 7). Small dark sand-grains are found scattered all over the upper 
surface. They add considerably to the darkness and opacity of the test. The bodies of 
the Ascidiozooids are of a dull yellow colour, and they are only seen indistinctly without 
dissection (PI. XXY. fig. 7). No common cloacal apertures are visible. 
The test, although it forms a large mass, is soft and is very readily torn, and even the 
presence of the imbedded sand fails to render it firm. In the outer layer where the test 
cells are very abundant and most of them fusiform and arranged with their long axes parallel, 
the matrix is slightly fibrillated. In other parts it is clear and apparently structureless. 
The body of the Ascidiozooid is of very irregular form (PI. XXV. fig. 9). In a 
specimen 7'5 mm. in length the thorax measured 2’5 mm., the abdomen 2 mm., and the 
post-abdomen 3 mm. The breadth varies greatly in the different regions. The thorax 
is nearly cylindrical, but the abdomen and post-abdomen are both irregularly swollen 
(PI. XXV. fig. 9, th., ab., 2 xah.). 
The muscle fibres in the mantle are large (PI. XXV. fig. 9, th.), but there are com- 
paratively few in each bundle, and the bundles are not very closely placed. The atrial 
aperture is provided with a short pointed atrial languet. The branchial aperture is 
surrounded by six broad low lobes (PI. XXV. fig. 9, hr.l.). The sphincter is well 
developed. In the post-abdomen the muscle bands are feeble but very closely placed, 
they are aU longitudinal in direction. 
The transverse vessels of the branchial sac are wide, and have well-marked horizontal 
membranes (PI. XXV. fig. 8, h.m.). The fine longitudinal vessels are wider than the 
stigmata. The endostyle is large and conspicuous, its course is undulating (PI. XXV. 
fig. 9, en.). 
The stomach is of large size and almost sjDherical, it is thick walled but smooth 
(PI. XXV. fig. 9, St.). The intestine is long, it forms a narrow loop. The alimentary 
canal is so placed that the stomach lies not only on the ventral side of but anteriorly to 
a part of the rectum (PL XXV. fig. 9, st. aud i.). 
