202 
THE VOYAGE OF H.M.S. CHALLENGER. 
The Mantle is fairly strong. The muscle bands are delicate but rather closely placed. 
They run chiefly in a transverse direction on the thorax. 
The Branchial Sac is large and has many stigmata. The transverse vessels are wide 
and are all of the same size. The stigmata are very long and narrow. They are arranged 
with regularity. 
The Endostyle is conspicuous. It has a very undulating course. 
The Dorsal Lamina is composed of long triangular languets with pointed ends. 
The Tentacles are large. There are about eight very long and the same number of 
smaller ones placed alternately. 
The Alimentary and Reproductive Viscera are closely placed, and form a large opaque 
mass tapering tow’^ards the posterior end. 
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. 
This species is represented by a large irregularly shaped mass and a few small lumps, 
aU obtained from Station 320, ofi* the east coast of South America, at a depth of 600 
fathoms. The large mass, from which the measurements given above are taken, 
incrusts a fragment of a corallum^ (PI. XXVII. fig. 3), while the smaller colonies are 
attached to pieces of a Polyzoon. The smaller specimens are merely rounded lumps, and 
they agree in other particulars with the larger colony. The colour is a dark grey, which 
is produced by the test, while the bodies of the Ascidiozooids show through as patches 
of a lighter and slightly yellowish grey. No common cloacal apertures are visible, but 
the surface is not in perfect condition, being torn in places and somewhat distorted. 
The Ascidiozooids are scattered apparently quite irregularly, and are fairly numerous 
(PI. XXVII. fig. 3). They dip into the mass at various angles and are of different 
lengths. The anterior part of the body which shows through the transparent upper 
layer of test is from 1 mm. to 3 mm. in its greatest length. 
The -test is very soft, and as there is a good deal of it the colony as a whole is soft 
and easily deformed. It has evidently become considerably flattened and distorted in 
places from pressing against the sides of the bottle in which it was preserved. The 
outer layer of the test very readily tears off as a thin membrane ; it is perfectly trans- 
parent. In this many sand-grains and fragments of sponge spicules and other foreign 
bodies are imbedded (see PI. XXVII. fig. 4, where o.s. indicates the outer surface), and 
they are even found more rarely in the deeper layers of the test. The cells are parti- 
cularly large, and give off very long and much-branched processes (PI. XXVII. fig. 4, t.c). 
The colony is not attached by the entire lower surface. The rounded growing edges, 
which contain smaller and more regularly arranged Ascidiozooids, project freely and 
are not attached. The upper central part of the large colony has some of its Ascidio- 
1 Belonging to one of the Stylasteridae. 
