302 
THE VOYAGE OE H.M.S. CHALLENGER. 
Leptoclinum japonimim, n. sp. (PL XXXIX. figs. 1-7). 
The Colony is massive and of rudely ellipsoidal form. It was attached by a rather 
small concave area on the lower surface. The upper surface is strongly convex. It is 
even and fairly smooth. The colour is a dark greyish-brown. 
The length is 1'4 cm., the breadth is 2 ‘2 cm., and the thickness is 7 mm. 
The Ascidiozooids are small and very numerous. They are scattered evenly all over the 
surface of the colony. No common cloacal apertures are present. The bodies of the Ascidio- 
zooids are rather short, they are divided into two regions, the thorax and the abdomen. 
The Test is firm but not hard. It is of a greyish-brown colour and nearly opacpie. 
The matrix is densely crowded with test cells, and contains also calcareous spicules. 
Bladder cells are present in some places. The spicules vary greatly in size and shape, 
and are only present in the upper layer of the colony. 
The Mantle is moderately strong. The muscle bands are narrow but regular. 
The Branchial Sac is well developed. There are four rows of short stigmata. The 
transverse vessels are moderately wide and have muscle fibres. 
The Tentacles are short, and are irregular in size and arrangement. 
The Alimentary Canal is not large. It forms a short wide loop. 
The Reproductive Organs are conspicuous. The testis is large, and it has the long 
vas deferens coiled spirally around it. 
Loccdity. — Station 233a, May 19, 1875 ; lat. 34° 38' N., long. 135° 1' E. ; depth, 
50 fathoms ; bottom, sand. 
One colony of this species was dredged off Kobe, Japan, from a depth of 50 fathoms. 
In external appearance it is not unlike Leptoclinum jacksoni from Australia, but the 
resemblance is merely superficial, and the colour is darker in the present species. 
The colony is massive (PL XXXIX. figs. 1, 2). It has evidently been attached to 
some convex body, as the small area of attachment at the posterior end is decidedly 
hollow (PL XXXIX. fig. 2). The upper surface is smooth and rounded, and has the 
small Ascidiozooids distributed evenly over it. They show as small rounded spots of a 
lighter colour than the surrounding test (PL XXXIX. fig. 1). 
The test is relatively large in amount. The matrix appears structureless. The test 
cells are very abundant and show a great variety in form (PL XXXIX. fig. 3, t.ci) ; 
fusiform, stellate and branched shapes predominate. Bladder cells, though present 
(PL XXXIX. fig. 3, 6L), are not very abundant. 
The spicules are fairly numerous in the superficial layer of the colony, but become 
veiy scarce or disap]jear in the deeper parts. Figure 3 represents part of a section 
through the test deep down in the colony where the spicules are absent. The shape of 
the sj)icules varies very greatly (PL XXXIX. fig. 6). Most of them are stellate but 
irregular, having the rays of dificrent sizes and shapes. Some simple forms are found 
