REPORT THE TUNICATA. 
95 
Axatomy. 
The colony of this species (PI. X. fig. l) agrees with that of the last in being more 
or less club-shaped, but generally shows more resemblance to an elongated head of clover 
borne on a thickened stalk. The stalk (PI. X. fig. 3) is of a dirty white colour, is thick, 
bent, and twisted, and has an irregular surface, generally grooved longitudinally. 
Compared with the last species it is short in proportion to the size of the head, and 
instead of tapering downwards rather increases in diameter as it approaches the base, 
which is a thickened bulb generally covered with adhering sand-grains, shells, zoophytes, 
&c. (PI. X. fig. 1), showing that this end was attached or imbedded in the sea-bottom. 
On account of the curvature of the stalk, the comparatively large head hangs downwards, 
its apex probably having been close to the ground. The colour of the stalk is the same 
in all the specimens, and no structure is visible from the outside. The head (PI. X. 
figs. 1, 2) is more elongated than in the last species, and is generally thickest a short way 
from the base ; from this point it tapers to the rounded apex. The investing mass is 
almost perfectly transparent. The Ascidiozooids are seen as dull white elongated patches 
arranged in spiral lines (PI. X. figs. 1, 8). They are largest at the upper end of the 
colony, where, though arranged more openly (PI. X. fig. 2), they extend almost to the 
summit, there being little or no bare patch as in the last species. At the base of the 
head they are smaller and are placed closer together (PI. X. figs. 3, 7), but the difierence 
in size is usually not very striking. 
Almost the entire thorax of each Ascidiozooid is seen (PI. X. fig. 8), and the two 
apertures, the sinus over the ganglion, and the endostyle, are easily distinguishable. The 
Ascidiozooids are placed so that the thorax inclines upwards and outwards (PI. X. 
fig. G), and as the endostyle may be seen running along the outermost edge of the 
thorax it follows that the atrial aperture and therefore the dorsal side of the Ascidiozooid 
is next the summit of the colony. The space between the Ascidiozooids seen through the 
transparent investing mass is of a dull indigo colour : this gives the head its characteristic 
bluish tint. 
As in the last species the Ascidiozooids are arranged round the periphery of the 
head, the centre of which is occupied by an investing mass traversed by the vascular 
appendages attached to the posterior ends of the Ascidiozooids. The investing mass 
of the central region has a hyaline appearance, but is not so transparent as the part 
occupying the peripheral zone. 
The Ascidiozooids are much larger than those of the last species, and are placed more 
vertically in the colony, in consequence of which they overlap, the abdomen of one being- 
covered by the thorax of the next below (PL X. figs. 6, 7). On account of the small size 
of the incubatory pouch in this species, the embryos do not form a naked eye feature, the 
whole extent of the sections being occupied by the Ascidiozooids and the investing mass. 
