EEPOET ON THE TUNICATA. 
185 
structure. Two colonies of about the same size were obtained near Marion Island, between 
the Cape of Good Hope and Kerguelen Island, in from 50 to 75 fathoms of water. 
There is no peduncle, the pale grey rounded mass being simply attached by a 
small portion of its surface (PI. XXY. fig. 4). The colour may become darker in 
places from the presence of small patches of minute sand-grains adhering to the surface. 
The systems are clearly visible on the uj^per part of the colony, as the anterior ends of 
the Ascidiozooids show through the transparent test very distinctly. The bodies are 
unusually elongated. A specimen 9 mm. in length has the thorax 2*5 mm. in length, the 
abdomen 2'5 mm., and the post-abdomen 4 mm. The thorax is the widest part (PI. 
XXV. fig. 6, th.). 
The outer layer of the test is rather firmer than the inner part. The test cells are 
mostly of rounded form, though some are stellate or branched. The protoplasm of these 
cells is generally coarsely granular. 
The muscle bands in the mantle are all delicate, and on the abdomen and post- 
abdomen they are particularly narrow. The branchial siphon is short, and the sphincter 
muscle is not well developed. The branchial aperture is obscurely six-lobed. The atrial 
aperture is placed at the end of a siphon and is six-lobed. No atrial languet is present. 
Thebranchial sac is rather like that of Morchellium giarcli (compare figs. 2 and 5 on 
PI. XXV.). The transverse vessels are moderately wide (PI. XXV. fig. 5, tv.), and are 
provided with muscle bands having the arrangement around the rows of stigmata 
at the dorsal and ventral edges which is described on p. 182 (see PI. XXV. fig. 2, m.f.). 
The stigmata are equal in width to the fine longitudinal vessels. The dorsal languets 
are broader and very much shorter than those of Morchellium giarcli. The endostyle is 
conspicuous, its course is undulating. 
The oesophagus is a long narrow curved tube with the convexity dorsal (PI. XXV. 
fig. 6, oe.). It enters the stomach on its outer or dorsal edge about half way down. 
The stomach is nearly globular in shape, and has its wall thickened irregularly so as to 
form a number of short cjecal processes like those seen in the case of Morchellioides 
affinis and Morchellium giarcli. The cjeca are not arranged in rows (PI. XXV. fig. 6, 
st). The intestine is at first a wide tube. It runs directly backwards from the 
posterior end of the stomach for a short distance, and then turns ventrally and towards 
the right hand side to become the rectum ; the intestinal loop is very narrow, and 
the most posterior part of the intestine is of small calibre. The rectum is a large thin- 
walled tube. It runs forward on the ventral and right hand edge of the stomach, and 
then turns dorsally, crossing on the right hand side of the oesophagus. It runs for a 
short distance along the dorsal edge of the thorax, and then terminates by opening into 
the peribranchial cavity. 
The post-abdomen is separated from the rest of the body by a slight constriction. 
The reproductive organs in all the Ascidiozooids examined occupied only a small portion 
(ZOOL, CHALL. EXP. PART XXXVIII. 1885.) Pp 24 
