•216 
THE VOYAGE OF H.M.S. CHALLENGER. 
Amaroucium variahile, n. sp. (PL XXIX. figs. 7-12). 
The Colony consists of one or more masses of an irregularly ovate or pyriform shape 
attached by short peduncles. The upper end is broad and generally more or less convex. 
There may be slight lateral compression. The surface is generally rather uneven and not 
smooth. The colour is usually yellowish-grey, but may be darker. 
The length is 2 -5 cm., of which 5 mm. is formed by the peduncle; the greatest 
breadth is 1‘7 cm., and the thickness is about 1 cm. 
The Ascidiozooids are numerous and of large size. They are distinctly visible on 
the outside of the colony. They are usually about 6 mm. in antero-posterior length, and 
are placed with considerable regularity at right angles to the upper surface of the colony. 
The division of the body into regions is not distinct. 
The Test is firm and cartilaginous. It is of a yellowish-grey colour and is semi- 
transparent. The matrix is clear and structureless, but it is crowded with minute test 
cells of various shapes. There are no bladder cells, and no vessels are present. 
The Mantle is fairly strong. The musculature consists mainly of a series of longi- 
tudinally running bands of fibres placed at equal distances. 
The Dmnehial Sac is well developed. The transverse vessels are fairly wide and 
have muscle fibres. The stigmata are numerous, but small and inconspicuous. 
The Alimentary Canal forms a long narrow loop. The stomach is rather cylindrical 
in shape, and its wall is longitudinally folded. 
The Post- Abdomen is usually of large size. 
Localities. — {a) Kerguelen Island, 10 to 60 fathoms; (6) Kerguelen Island, 10 to 100 
fathoms; (c) Kerguelen Island, 28 fathoms; {d) Eoyal Sound, Kerguelen, January 19, 
1874, 20 to GO fathoms. 
I unite under this species a large number of specimens, collected in the 
neighbourhood of Kerguelen Island, which present great variations in form, size, colour, 
and some other particulars. They are, however, all closely related to one another, and 
although it might be possible to break them up into two or three species, I believe 
that the differences between the extreme forms are sufficiently bridged over by inter- 
mediate conditions to warrant one in regarding them as composing a single species only. 
They form an extremely interesting series on account of the way in which they 
illustrate individual variation. 
The shape may vary from almost spherical through ovate, ellipsoidal, discoid, 
and pyriform, to fusiform or wedge-shaped or , even quite irregularly elongated forms. 
The woodcuts (fig. 9, a to 1) show a few of the most striking forms assumed by the species. 
There are upwards of thirty colonies altogether in the collection, and no two of them 
have tlie .same sliape. In most cases the colony consists of one mass only, and is attached 
l>y a longer or shorter peduncle (fig. 9, h, c, g) ; sometimes the peduncle is prolonged 
