226 
THE VOYAGE OF H.M.S. CHALLENGER. 
defined (PL XXX. fig. 8), while others in the neighbourhood are less definite. In other 
parts of the colony the Ascidiozooids are apparently placed quite irregularly, as in the 
other specimens of the species (see PI. XXX. figs. 1, 2). Here, as in so many other cases, 
it is impossible from want of material to decide whether it is most convenient to 
regard this form as merely an individual variation, or as a specimen of a distinct variety 
Worthy of being named. 
Amaroucium 20 cdlidulum, n. sp. (PL XXX. figs. 9-11). 
The Colony has the form of a rudely hemispherical mass, attached by about half of 
the fiattened lower surface, and irregularly convex above. There is slight lateral 
compression, and the edges are all rounded. The colour is light grey, with pale yellow 
patches here and there where the Ascidiozooids show through the test. The surface is 
uneven, and is finely roughened all over. 
The length (from the base upwards) is 1‘5 cm., the breadth is 3 cm., and the 
thickness is 2 cm. 
The Aseidiozooids are fairly large and not very numerous. An average size is about 
8 mm. in antero-posterior length and 1*5 to 2 mm. in greatest breadth. The body is 
not distinctly divided into regions, and the post-abdomen is thick. The whole body of 
the Ascidiozooid is of an opaque, pale, whitish-yellow colour. There is no arrangement 
in systems. 
The Test is firm and tough. It is of a light grey colour and rather transparent. 
The test cells are very minute and not very numerous ; there are no bladder ceUs 
present. 
The Mantle is well developed and strongly muscular. Most of the muscle bands run 
longitudinally. 
The Branehial Sac is thick-walled and opaque. The stigmata are small and rounded, 
and the transverse vessels are aU of the same size. 
The Endostyle is broad and conspicuous, and has an undulating course. 
The Tentacles are numerous and closely placed,. They are of two sizes, placed 
alternately. 
The Dorsal Tubercle has a plain circular aperture, and is placed close to the 
peripharyngeal band. 
Zoc«%.— Station 315, January 26, 1876; lat. 51° 40' S., long. 57° 50' W.; 
depth, 12 fathoms ; bottom, sand and gravel. 
I he single specimen of this species in the collection, is a small irregularly rounded 
massive colony obtained at Port William, in the Falkland Islands, from a depth of 5 to 10 
fathoms. It was attached l:)y a part only of the lower surface, the edge all round being 
