REPOET ON THE THHICATA. 
287 
It acUieres to a fragment of Sponge, round one branch of which it has grown so as to 
completely incrust it (PL XXXYIII. fig. 10). The edges are free rounded projections 
containing no Ascidiozooids. Over the rest of the surface the Ascidiozooids are closely 
placed. They are conspicuous externally and form small circular grey dots about 
0’2'5 mm. to 0'30 mm. in diameter. The common cloacal apertures are 1 mm. to 1'5 mm. 
in length. 
The spicules in the test are very abundant. They vary a little in size, but are very 
regular in form (PI. XXXYIII. fig. 13); no spherical spicules were noticed. In the 
surface layer of test the spicules are less crowded over the bodies of the Ascidiozooids 
than between them (PL XXXYIII. fig. 11), consequently the appearance of a strong 
network with circular spaces is produced just as in the case of Leptoclinum tenue and 
some other species, but in the present case the areas occupied by the Ascidiozooids are 
relatively much smaller, and the dark masses of test between are larger (PL XXXYIII. 
fig. 11). The edges of the six lobes surrounding the branchial apertures are strengthened 
by fines of closely placed spicules (PL XXXYIII. fig. 12); the base of the lobe has 
generally few or no spicules. 
The branchial sphincter is very large (PL XXXYIII. fig. 12, spli.), but otherwise the 
muscular system is not strong. 
The branchial sac has long stigmata with pointed ends. They are regularly arranged, 
and their ciliated ends ai'e large, and have pointed free ends. The endostyle is large 
and conspicuous. Its course is slightly undulating. 
The nerve-ganglion is an ellipsoidal mass, placed close to the peripharyngeal band. 
The stomach is small. The intestine is long and narrow, and the intestinal loop is 
very slight, the rectum being placed close to the intestine and stomach. The rectum 
contains dark-coloured fsecal pellets. The testis is large and has a spirally coiled 
vas deferens. No ova and no embryos were discovered in the colony. 
Leptoclinum albidum, Yerrill (”?). 
Leptoclinum albidum, Verrill, Brief Contributions to Zoology, &c., Amer. Journ. Sci. and Arts, 
ser. 3, vol. i. Ho. 6, p. 443, June 1871. 
The Colony is a thin expanded layer of irregular shape. It is incrusting, and is 
attached by its entire extent. The upper surface is uneven but moderately smooth. The 
colour is a dull greyish-white. 
The length is about 5 cm., the breadth about 3 cm., and the thickness about 1 mm. 
The Ascidiozooids are very numerous and of rather small size. They are usually dis- 
tributed evenly over the upper surface of the colony. Common cloacal apertures are 
usually visible. The Ascidiozooids are placed nearly vertically in the colony, and their 
bodies are divided into two regions — thorax and abdomen. 
