REPORT ON THE TCJNICATA. 
49 
The colour of the part of the colony where Ascidiozooicls are present is pretty 
uniformly of a reddish-purple (PL I. figs. 6, 7), while the edges where the test is 
free from Ascidiozooids is greyish, marked in places either with yellow dots, or opaque 
grey dots. The anterior ends of the Ascidiozooids, although lighter than the rest of the 
body, are not nearly so light as in Botrylloides perspicuum. From all this it is obvious 
that the present specimens difier considerably from Botrylloides perspicuum in external 
appearance (compare PI. I. fig. 4 vdth PI. I. figs. 6, 7), but on account of the 
great similarity in their internal structure I have placed them under the latter species 
as a variety, until the examination of additional specimens of both forms gives us a more 
complete knowledge of the range of individual variation, and of the exact colouring of 
the colonies in the living condition. 
Although the colonies of the variety are all of small size, still one can see from the 
arrangement of the Ascidiozooids in the systems that it is a Botrylloides. The lines, 
however, are not so long and winding as in Botrylloides purpureum, and no large spaces 
are enclosed by them as in Botrylloides perspicuum and Botrylloides gascoi. 
The cells of the test are very inconspicuous, and the matrix is homogeneous and 
transparent. The vessels are numerous but delicate. Their terminal knobs, which are 
found chiefly close to the surface, vary greatly in form and size (PI. III. fig. 18, t.L). 
They are sometimes globular, sometimes ovate, and sometimes of an elongated pyriform 
shape, and occasionally very irregular. The pigmented corpuscles are not so large as in 
Botrylloides perspicuum, and they are of a pale yellow colour. The mantle is only 
slightly pigmented. In some cases it is scarcely coloured at all. 
The branchial sac (PI. III. fig. 15) is very like that of Botrylloides perspicuum. 
It is large and has many rows of regularly placed stigmata. There are usually four or 
five stigmata between the endostyle and the most ventral of the internal longitudinal bars. 
The endostyle is narrow. 
The dorsal tubercle (PI. III. fig. 16, d.t.) is exactly like that of Botrylloides per- 
spicuum, and occupies a position unusually far from the dorsal lamina. 
The alimentary canal (PI. III. fig. 17) occupies only the posterior part of the 
Ascidiozooid. The oesophagus runs posteriorly and ventrally, and is moderately long. 
The angle varies somewhat in different individuals (compare figs. 14 and 17 in 
PI. IIP). The stomach is large and is strongly ribbed externally, especially at the 
oesophageal end, wFich is truncated and wider than the opjjosite end which tapers 
suddenly into the intestine (PI. III. fig. 17, i). There are usually five projecting folds 
on each side of the stomach. The intestine curves anteriorly and then dorsally and 
a little posteriorly to come in contact with, and in some cases (PI. III. fig. 17) 
considerably overlap, the anterior edge of the stomach. It then turns dorsally and 
anteriorly to become the rectum, which after a very short course ends not far in front of 
the oesophageal aperture. 
(ZOOL. CHALL. EXP. PART. XXXVIII. 1885.) Pp 7 
