REPORT ON THE TIJNICATA. 
293 
place where the spicules in the surface layer of the test over the Ascidiozooid become 
greatly reduced or altogether cease, while the inner is the branchial sphincter. 
The distribution of the spicules in the surface layer of test is also distinctly seen in 
a low power view of the colony (PI. XXXV. fig. 12). They are most abundant between 
the bodies of the Ascidiozooids, where the dark opaque lines form a network with fairly 
regular hexagonal meshes. The regions occupied by the Ascidiozooids are thus clearly 
marked out (PI. XXXY. fig. 12). A higher magnification shows that the branchial 
aperture is irregularly six-lobed (PI. XXXV. fig. 13, hr.). The bases of the lobes are 
usually strengthened by a few spicules, which are arranged in two, three, or four groups 
(generally three) ; these are shown as small dark masses on the line of the sphincter 
muscle in figure 12. 
The spicules have the rays more tapering and the apices sharper (PI. XXXV. fig. 14) 
than is usual amongst alhed forms. The mantle has both transverse and longitudinal 
muscle bands (PL XXXV. fig. 13). 
The branchial sac has small but well-formed stigmata ; the ciliated cells are distinct. 
The testis is large, and the vas deferens is spirally coiled around it. No ova nor 
embryos were discovered in the colony. 
Leptoclinum suhflavum, n. sp. (PI. XXXVIII. figs. 14-18). 
The Colony is a thin incrusting layer of irregular shape, attached by its entire extent. 
The upper surface is even, but rather rough. The colour is yellow. 
The length is about 2'5 cm., the breadth about 2 cm., and the thickness is less than 
1 mm. 
The Ascidiozooids are moderately large, and fairly numerous. They are closely 
placed all over the surface, and are not arranged in definite systems. No common cloacal 
apertures are visible. 
The Test is rather firm. It is of a greyish-yellow colour and is transparent. The 
matrix is crowded with test cells which are mostly of large size and rounded form. 
Calcareous spicules are also present, but they are most irregular in size and shape. They 
are never stellate. 
The Mantle is moderately strong. The muscle bands are delicate but numerous. 
They are mostly longitudinal in direction, and are placed regularly. 
The Branchial Sac is rather small and is thick-walled. The stigmata are usually 
small, but are arranged with regularity. There are four rows. The ciliated cells are distinct. 
The Dorsal Lamina is represented by a series of rather short tentacular languets. 
The Tentacles are short and stout. There are from twelve to sixteen of them. 
The Alimentary Canal is moderately large. It forms a short loop. 
Locality. — Kerguelen Island; depth, 28 fathoms. 
