172 
THE VOYAGE OE H.M.S. CHALLEHGEE. 
None of these have any localities attached to them, but most of them are merely pieces 
taken from colonies which occur in the collection, and therefore they can be readily 
referred to their proper species and localities. In the case of the present specimen, 
however, and one or two others, there is nothing else belonging to the same species in 
the collection, and therefore there is no clue to the locality from which it was obtained. 
The specimen is a slice cut out of a large colony, and measures rather more than 
9 cm. in length by about 4 cm. in greatest breadth and 1 cm. in thickness. From the 
shape of the specimen it is probable that the colony was a large rounded mass, and 
there is no evidence in favour of its having been pedunculated. It is impossible to 
say whether the colony was elongated from the base upwards or not, as, on account of 
the irregularity in the arrangement of the Ascidiozooids, it cannot be determined with 
certainty whether the slice was cut from the colony longitudinally or transversely.^ 
The colour on the outside is simply that of the test, a warm light grey, as the Ascidio- 
zooids are so scattered and so deeply placed in the colony as scarcely to show through at 
all. The large Ascidiozooids are of an opaque yellowish-brown colour, and are placed 
very irregularly in the test (PI. XXIV, fig. 11). The body is nearly cylindrical and is 
not divided externally, but dissection shows that the branchial region occupies the 
anterior half or so, and the intestinal and genital parts the remainder. 
The test is very compact, and has quite a cartilaginous feeling. It is of the same 
colour and structure throughout. The sinall test cells are very numerous, and in some 
places are densely crowded. No vessels are visible. 
The mantle is not so thick as might be expected from the size and opacity of the 
body. The longitudinal muscle bands on the thorax are moderately strong, but they do 
not form a continuous layer. On the abdomen they become much thinner and gradually 
die away. The branchial siphon has six lobes, and the sphincter is well developed. 
There are about twenty rows of stigmata in a large sized branchial sac, and there are 
usually about twelve in each row. The stigmata vary considerably in size in different 
sacs (see PI. XXIV. figs. 12, 13, sg.), probably to a great extent according to the size 
and age of the Ascidiozooids. Figure 12 shows an average sized set of stigmata, while 
figure 13 was probably taken from a very young branchial sac. The endostyle is large 
and conspicuous, and has an undulating course. 
The languets are tentacular in form, but very short (PI. XXIV. fig. 14, 1.) and 
rather closely placed. They are united by a distinct membrane (the dorsal lamina, 
PI. XXIV. fig. 14, d.L), behind which is placed a band of muscle fibres (m.f.). 
The alimentary canal forms a long narrow loop. The stomach is long and has its 
thick wall folded transversely as in Atojwgaster aurantiaca. The intestine is rather 
narrow, and undulates considerably in its course. 
' I am inclined to think that it must have heen a slightly oblique longitudinal section. If so, the colony would 
probably have been about 10 cm. in length and 4 cm. in breadth. 
