•264 
THE VOYAGE OF H.M.S. CHALLENGEE,. 
the older ones — after having produced ova in their younger stage — function as males 
only. Two ova were found far forwards alongside the rectum in the Ascidiozooid 
figured (PI. XXXIV. fig. 2, o.). No larvae were discovered in the colony. 
Didemnum aurantiacum, n. sp. (PI. XXXIII. figs. 1-8). 
The Colony is a large irregularly convex mass incrusting various foreign bodies. Its 
upper end is rounded and roughly hemispherical. The lower part is irregular. The 
surfiice is even but slightly rough. The colour is an orange-brown. 
The leuffth is 4 cm., the greatest breadth is 5 cm., and the thickness is 2’ 5 cm. 
The Ascidiozooids are numerous but very small, and they are placed with great 
regularity over the surface. They are of rounded form, and the body is not distinctly 
divided into regions. 
The Test is thick and solid. It is firm and opaque. The outer part is of a dull orange 
colour, while inside it is light grey and semi-transparent. The matrix is apparently 
structureless. The test cells are abundant and of large size. The spicules are colourless, 
and are numerous on the surface, but much fewer in Humber deeper down. They 
are usually of stellate form, with moderately long rays, but occasionally spherical ones, 
with very short blunt rays, are met with. 
The Mantle is strongly mnscular. 
The Branchial Sac is small and of rounded form. The stigmata are minute and 
inconspicuous. 
The Endostyle is large and of considerable width. Its course is straight. 
Locality . — Station 162, April 2, 1874 ; lat. 39° 10' 30" S., long. 146° 37' 0"E. ; depth, 
38 fathoms ; bottom, sand and shells. 
A single specimen of this species was dredged in Bass’ Strait, south of Austraha, 
from a depth of 38 fathoms. It is a handsome colony, roughly of hemispherical form 
(PI. XXXIII. fig. 1), and having a dull orange-brown colour, darker in some places and 
lighter in others. 
The Ascidiozooids are placed with great regularity over the surface, where their 
anterior ends form minute projections from 0'5 mm. to 1 mm. apart (see PI. XXXIII, 
fig. 1). There is apparently no arrangement in systems, and no common cloacal apertures 
are visible in the specimen. The branchial apertures, when viewed from the outer surface 
(PI. XXXI n. fig. 3), are usually of an irregularly hexagonal form. 
The surface layer of test is stiff and opaque, and contains abundance of spicules 
(see PI. XXXIII. fig. 2). These spicules are quite colourless, and although they may aid 
in producing the opacity of the test, its dull yellow colour is certainly not due to their 
presence, but is caused by a homogeneous yellow tint in the matrix. The coloured 
