REPORT ON THE TUNICATA. 
343 
smaller transverse vessels crossing each mesh but not interrupting the stigmata. The 
meshes are square, and contain each about six long narrow stigmata. 
The Dorsal Lamina is a plain narrow membrane. 
The Tentacles are of two sizes, placed alternately ; they are numerous, and the larger 
ones are of considerable size. 
Die Dorsal Tubercle is small, and has an inconspicuous rounded aperture placed close 
to the anterior end of the dorsal lamina. 
The Alimentary Canal is moderately large. It forms a narrow loop. The stomach 
is large and has well-marked longitudinal folds. 
Die Reproductive Organs are in the form of polycarps, which project from the inner 
surface of the mantle. They are unisexual, and the male and female polycarps differ in 
form. Endocarps are also present. 
Localities. — (a) Station 313, January 20, 1876 ; lat. 52° 20' S., long. 67° 39' W. ; 
depth, 55 fathoms; bottom, sand; bottom temperature, 47°'8 F. [h) Samboangan, in 
the Philippine Islands ; depth, 10 fathoms. 
A considerable number of specimens of this species were obtained off Cape Virgins, 
at the extremity of the Strait of Magellan, from a depth of 55 fathoms, and one small 
colony, which seems not to be distinguishable specifically from the others, was obtained 
off Samboangan, in the Philippine Islands, at a depth of 10 fathoms. 
Most of the specimens from the Strait of Magellan are attached to large individuals 
of Molgida gigantea, and form incrusting layers over the upper part of the test. The 
edges of the colony are in some places very thin sj^reading membranes composed of 
test only, while in other places they form free projecting lobes and contain Ascidiozooids. 
A few of the colonies are not incrusting, but project upwards from a small area of attach- 
ment in the form of more or less lobed flattened expansions (PI. XLVI. fig. 9). 
The dimensions given above are those of a small colony. Some of the incrusting 
specimens attain a much larger size (upwards of 20 cm. in length). The thickness varies 
somewhat. The colour is always greyish, but in some cases it is a slaty blue-grey, while 
in others it has a distinctly pink tint. The anterior ends of the Ascidiozooids are very 
conspicuous on the surface. In some colonies they occupy the entire surface of the 
colony, being merely separated by lines (PI. XLVI. fig. 9), but in others a small amount 
of investing mass of a distinctly lighter colour may be seen between the Ascidiozooids. 
The branchial and atrial apertures are obscurely four-lobed. They generally appear 
circular until carefully examined. 
The Ascidiozooids are flattened antero -posteriorly, a very rare condition amongst 
Compound Ascidians. They vary in size from 1 mm. to 8 mm. in greatest diameter. 
The smaller ones are mostly placed in the thin spreading margins of the colony, but 
they occasionally occur between larger Ascidiozooids in the centre of the mass. 
