REPORT 0 ^ THE TUHICATA. 
303 
of fusiform shape/ or consisting of two, three, or four rays only. Deformed and 
monstrous spicules also occur (PL XXXIX. fig. 6). 
The spicules in the superficial layer of test stop at a short distance from the 
branchial apertures (PI. XXXIX. fig. 5), just at the bases of the six large lobes. The 
greater part of each lobe is free from spicules, but the margin is bordered by a single row, 
and the apex contains a small mass of closely placed spicules. The result of this 
arrangement is. that the six rays or angles of the branchial apertures stretching out 
between the lobes are greatly emphasised, and are conspicuous in a low power view of 
the surface (PI. XXXIX. fig. 5). 
The musculature of the mantle is delicate but rather regular. Equidistant longi- 
tudinally running muscle bands are present on the thorax. At the anterior end they 
radiate from the base of the branchial siphon. The atrial siphon is placed on the dorsal 
edge of the thorax, half way down. 
The transverse vessels of the branchial sac are provided with strong muscle bands 
(PI. XXXIX. fig. 4, tr.). The stigmata are short, but numerous and regular. The 
ciliated cells are distinct (PI. XXXIX. fig. 4, sg.). 
The endostyle is large. The tentacles are of at least two sizes, but they are not 
arranged with regularity. The nerve ganglion is spherical. It is placed at the base of 
the branchial siphon. 
The alimentary canal is rather narrow. The oesophagus leads posteriorly from the 
branchial sac to the small globular or quadrate smooth-walled stomach. The intestine 
runs posteriorly from the stomach for a short distance and then sweeps round anteriorly 
in a wide open loop. The rectum lies alongside the oesophagus. 
The male reproductive organs are placed on the intestinal loop, behind which they 
project for a considerable distance, and so form the posterior end of the body. The testis 
is large and ovate, and the conspicuous vas deferens coils from six to eight times spirally 
around it (PI. XXXIX. fig. 7, v.d.). Xo ova and no embryos were discovered in any of 
the Ascidiozooids examined. 
Dg-)toclinum {?) jacksoni, n. sp. (PI. XXXVIII. figs. 19-22). 
The Colony is massive and of irregular .shape. It is attached by the greater part of 
the lower surface, which is strongly concave. The upper surface is irregularly conical ; 
it is fairly smooth. The colour is a dull greyish-white. 
The length is 1'7 cm., the greatest breadth is 2'5 cm., and the greatest thickness is 
1‘2 cm. 
The Ascidiozooids are small but very numerous. They are closely placed all over the 
' Poasitly these simple fusiform spicules are merely fragments of the ordinary stellate ones which have been broken 
off in cutting the sections. 
