EEPORT ON THE THNICATA. 
197 
rounded and lighter in colour than the other two. It is attached to sand-grains, &c., by 
a narrow area at the posterior end. A second colony is much longer but narrower 
(PI. XXYI. fig. 10). It is 2 cm. in length, 9 mm. in breadth, and 4 mm. in thickness. 
It has a long peduncle incrusted with dark coloured sand-grains. The third colony 
is much smaller, being 9 mm. in length, 8 mm. in breadth, and 5 mm. in thickness. 
It is darker in colour than the other two colonies. In all the specimens the upper 
surface where the anterior ends of the Ascidiozooids are placed is lighter in colour 
and softer than the rest of the colony. The surface is slightly roughened all over, 
and a few sand-grains are found adhering far above the base of attachment (PI. XXYI. 
fig. 10). 
The test is soft and is easily deformed, especially on the upper surface of the colony. 
Lower down the incrusting sand-grains make it stifier. The dull brown bodies of the 
Ascidiozooids show through it distinctly on the sides of the colony. They are not so 
clearly visible on the upper surface. 
There is no definite arrangement amongst the Ascidiozooids, but their anterior ends all 
point towards the upper surface, and their long bodies lie nearly vertically in the colony. 
As usual the muscle bands of the mantle almost die away on the abdomen, but 
become stronger again on the post-abdomen. The branchial aperture is distinctly 
six-lobed. The branchial sac is very rudimentary, but the endostyle is broad and 
conspicuous. 
The tentacles are exceptionally narrow, and some of them are of considerable length. 
There is no definite arrangement. 
The oesophagus leaves the posterior end of the branchial sac and runs backwards to 
open into the large ovate stomach. The intestine is narrow ; it arises from the posterior 
end of the stomach and turns almost at once dorsally and then anteriorly, forming a 
short but rather •wade loop. The rectum is large, it runs forwards alongside the stomach, 
oesophagus, and branchial sac, to open into the peribranchial cavity. 
The convoluted vas deferens is a conspicuous object in its entire length, both in the 
post-abdomen and also in its course alongside the rectum. 
There are two or three small irregular projections at the posterior end of the post- 
abdomen, which look like rudimentary vascular appendages. 
Polyclinum minutum, n. sp. (PI. XXY. figs. 10-12). 
The Colony is irregularly rounded in form, and is attached by a small area at one end. 
There is no lateral compression. The colour is dull yellowish-grey, and the surface is smooth. 
The length is 1 cm., the breadth 1‘3 cm., and the thickness Id cm. 
The Ascidiozooids are very small, about 3 mm. in length and 0‘5 mm. in greatest 
breadth. They are not numerous, and are scattered quite irregularly over the colony. 
