EEPORT OX THE THNICATA. 
165 
The length of the colony is 26 cm., the greatest breadth is 7 ’5 cm., and the average 
thickness is 4 cm. 
The Ascidiozooids are very long and narrow, and are placed more or less vertically 
in the test. They are arranged in circular systems, consisting each of from six to twelve 
Ascidiozooids arranged around a centrally placed common cloaca. The body is usually 
over 1 cm. in length, and consists of three well-defined regions. The thorax is about 
2 mm. in antero-posterior length, and rather more than 1 mm. in breadth (dorso- 
ventrally). The abdomen is narrower, and is usually 3 or 4 mm. in length, while 
the post-abdomen may be short — a few millimetres — but more usually extends as a 
narrow undulating thread for a considerable distance downwards into the colony. 
The Test is firm and cartilaginous but not hard. It is of a light grey colour, and is 
semi-transparent. The matrix is clear and homogeneous, and the small test cells are 
numerous. There are no bladder cells. 
The Mantle is not strong. The muscle bands run mainly in a longitudinal 
direction. They are narrow and not very numerous. 
The Branchial Sa,c is fairly large. The transverse vessels are wide, and are supplied 
with muscle fibres. The stigmata are wider than the fine longitudinal vessels, and are 
arranged with regularity. 
The Dorsal Lamina is represented by a series of pointed languets. 
The Tentacles are rather small, and they are not numerous. 
The Dorsal Tubercle has a small round aperture. 
Locality. — Station 313, January 20, 1876 ; lat. 52° 20' S., long 67° 39' W. ; 
depth, 55 fathoms; bottom, sand; bottom temperature, 47°’8 F. 
This is the largest Compound Ascidian in the Challenger collection, and, like so many 
other large Tunicata {e.y., Molgula gigantea and Goodsiria coccinea), was obtained in 
the Strait of Magellan. The colony is an elongated mass (PI. XXIII. fig. F), and was 
evidently attached by one end, upon which it stood upright in the water. The lower- 
end has small stones, sand-grains, &c., imbedded in it for a distance of from 1 cm. to 
3 cm., and some colonies of Hydroid Zoophytes are attached to this region. The widest 
point is about half way up, and from this region it tapers slightly both upwards and 
dovmwards equally till it reaches about 3 cm. from the top or the base. At these points 
the width is about 5 cm. The upper end has a rounded point. The colour is fairly 
uniform all over. The few places where a slight hyaline tint is seen are regions where 
there are no Ascidiozooids, and where therefore test alone is seen. The general roughness 
of the surface is caused in great part by the anterior ends of the Ascidiozooids usually 
projecting slightly beyond the level of the test, but besides this there are slight grooves 
and ridges, due possibly to the contraction of the test on being placed in alcohol. 
^ This figure represents the colony reduced to one half of the natural size. 
