EEPORT ON THE TUNICATA. 
409 
the left side, outside the loop of the intestine (see PL XLYII. fig. 6). A few also occur 
on the right side of the body. Each clump consists of a number of small rounded masses, 
united to the base of a short tubular duct (see PI. XLYIII. fig. 11) which opens into the 
peribranchial cavity. 
Bathyoncus minutus, n. sp. (PI. XLYII. figs. 7-10). 
External Appearance. — The shape is nearly discoid, and the body is flattened antero- 
posteriorly. It is attached by the entire lower surface. The margin is expanded and 
very thin. The apertures are placed on the upper surface, and are rather far apart. 
They are both of small size but distinctly fusible, and are placed upon slight papillae. 
They are not regularly lobed, but each aperture has a number of slight grooves radiat- 
ing from it. The surface is even, but minutely roughened. The colour is dark brown. 
The diameter of the body is 5 mm., and the thickness is about 0’5 mm. 
Tlie Test is stiff and somewhat brittle, but thin. It is leathery in consistence. It is 
of a yellowish-brown colour on the inner surface, but is darker in the neighbourhood of 
the apertures. The upper surface is raised into a u umber of small blunt projections, 
which are especially numerous around the apertures. 
The Mantle is closely united to the inner surface of the test. It is moderately 
muscular. There are a number of longitudinal bauds which radiate from the two aper- 
tures ; these, with the circular muscle bands, form a network over the anterior part of the 
body (see PI. XLYII. figs. 9, 10). The sphincters around the apertures are rather strong. 
The Branchial Sac appears to have no folds. The transverse vessels and internal 
longitudinal bars are few in number, but wide ; they form large meshes. 
The Dorsal Lamina is a plain membrane. 
The Tentacles are few and simple. They ain of two sizes, which occur alternately. 
The Alimentary Canal is short and has no complications. It forms a simple loop. 
The Reproductive Organs form a single mass attached to the mantle. 
Locality. — Station 253, July 14, 1875; lat. 38° 9' N., long. 156° 25' W. ; dejDth, 
3125 fathoms ; bottom, red clay; bottom tem23erature, 35°4 F. 
One specimen of this small species was obtained attached to a nodule of manganese 
dredged in the North Pacific Ocean from the great depth of 3125 fathoms. The st^ecimen 
had been detached and mounted in glycerine as a microscope slide before it came into my 
hands. It is almost perfectly flat now (PI. XLYII. fig. 7), but I am inclined to think that 
it has been squeezed while mounting, and is really unnaturally flattened and somewhat 
distorted. The lower surface by which it was attached is black, and has small particles 
of the manganese still attached to it ; the upper has the thin and irregularly expanded 
margins black, while the central part which, when living, was probably slightly convex, is 
of a brown colour. The two apertures are placed at the edges of the brown part of the 
(ZOOL. CHALL. EXP. — PAET XXXVIII. — 1886.) Pp 52 
