466 
Proceedings of the Royal Society 
ventral edge, and a little in front of the middle. Both apertures 
rather depressed and concealed. Surface very irregular, grooved and 
mamillated ; Synascidice, annelide-tubes, &c., adhering to it. Colour 
light yellowish-grey, not opaque, rather hyaline at the edges, and 
showing everywhere numerous blood-vessels ramifying near the 
surface. The terminal twigs of the vessels with their swollen ends 
are a prominent feature. Length, 9 cm. ; breadth, 5 - 6 cm. 
Test solid looking, varies in thickness from less than *5 mm. on the 
right side behind the middle to 1 - 5 cm. on the left side near the 
place of attachment. Apertures lobed indistinctly ; vascular trunks 
enter on the left side near the ventral edge and branch usually 
dichotomously, the terminal twigs ending in swollen knobs. The 
test shows no bladder cells. It contains the small spherical fusiform 
and stellate cells, and many minute granules. Crystals or concretions 
are also present,' generally in the form of short rods and crosses. 
One specimen, the test only, from .Royal Sound, Kerguelen Island, 
28 fathoms. 
It may be considered a somewhat doubtful proceeding to describe 
an ascidian from the test alone, and certainly in most cases it would 
not be proper. Still this specimen possessed such well-marked 
characteristics that I was tempted to give it a name. I believe that 
the test is distinct from that of all known species, and that when 
other specimens are found they will be easily recognised. It differs 
from Ascidia arachnoidea in the general shape and the position of 
the apertures. 
Ascidia nigra , Savigny. 
One specimen labelled, ‘‘Bermuda, shallow water.” Length, 6 
cm. ; breadth, 4 cm. 
Ascidia translucida , n. sp. 
External appearance .- — Shape ellipsoidal, oblong-ovate to oblong ; 
both ends rounded. Attached slightly by left side near base. 
Apertures sessile, placed on the right side. Branchial nearly terminal 
and median. Atrial more than a third of the way down, midway 
between the centre and the dorsal edge. Surface smooth and glossy. 
Colour very light grey, almost transparent, marked on the left side 
and the margins by white vascular ramifications. Length, 2 '2 cm. ^ 
breadth, 1*2 cm. 
