REPORT ON THE TUNICATA. 
123 
the intestine, 'U'hich it crosses about the level of the oesophagns, so as to come to lie on 
the dorsal edo-e of tlie rectum, along; which it runs to its termination. 
No incubatory pouches or larvae were found in the colony. 
Colelln concreta, n. sp. (PI. XVI. figs. 8-1 G). 
The Colony takes the form of a number of irregularly club-shaped masses united 
together by their lower ends, where they are attached to some foreign object. Each club- 
shaped mass consists of an upper more or less rounded head, the part occupied by the 
bodies of the Ascidiozooids, and a thick irregular stalk tapering downwards to the point 
of attachment. 
The general colour is yellowish-grey. The test of the head is light grey, 
while the Ascidiozooids show through as opaque light yellow bodies. The surface 
of the head is even and smooth ; that of the stalk is slightly uneven in places and not 
very smooth. No common cloacal apertures are visible. 
The average length of one of the club-shaped masses is about 3 cm. The length of 
the head is usuallv about 8 mm., its breadth 13 mm., and its thickness 11 mm. The 
usual length of the stalk is 2 cm., its breadth at the top 6 mm., at the base 2 mm. 
The Ascidiozooids are elongated antero-posteriorly, and are placed mostly at right 
angles to the upper surface of the colony. They are about 3 mm. in length and 1 mm. 
in greatest breadth. The anterior end is moderately wide. It bears both apertures. The 
thoracic region is usually not quite so large as the abdomen. The posterior end is narrow, 
and is continued into a slender vascular appendage which extends downwards through 
the test, usually for about 3 mm., and then terminates in a bulb. 
27/ e Test is very soft and delicate. The outer layer on the upper surface of the 
head is smooth and glistening, and is firmer than the deeper parts. The stalk is stronger 
than the test of the head, and is more opaque. 
The matrix is homogeneous, and contains great numbers of rather large fusiform and 
stellate cells. No bladder cells or pigment cells are present. 
The Mantle is fairly strong on the branchial part of the body ; over the viscera it is 
thin and membranous. The chief muscle bands run transversely and are regularly placed. 
The Branchial Sac is small and thick walled. It contains about eight rows of 
stigmata on each side. The alternate transverse vessels are larger than those between 
them. The stigmata are rather narrow and are closely placed. 
The Endostyle is very conspicuous. Its' course undulates greatly from side to side, 
especially towards its posterior end. 
The Dorsal Lamina is formed of a series of large pointed triangular lauguets. 
The Tentacles are not large, but they are fairly numerous. There are about sixteen, all 
of the same size. 
