OF THREE AUSTRALIAN SPECIES OF TUNICATA. 369 
gently curved, and ornamented with yellow vascular lines. The curvature of these beau- 
tiful organs is due to the presence of longitudinal muscular fibres on the concave border, 
having no others to antagonize them on the opposite side. 
The branchial network is minute and regular, and the membrane is thrown into about 
fourteen longitudinal folds; seven on either side of the body extending between the 
branchial and oral apertures, and increasing in length from before backwards, in which 
direction also they gradually become more curved. 
The mouth is small and surrounded by the converging ends of the longitudinal folds of 
the branchial membrane, leading into a short esophagus, which curves downwards and 
backwards to join an elongated stomach, from whose tapering pyloric end the intestine 
takes a very similar course to that described in the former case, and terminates in the 
cloacal chamber near the position of the mouth. 
The liver consists of numerous short and compressed glandular sacculi of a rich brownish- 
. red colour, lying on the left side and along the inferior border of the stomach, into which 
their contents are poured. 
The products of digestion are usually to be seen in the intestine, connected together by 
a plastic substance, and rolled into a filiform, continuous, and highly convoluted mass, 
extending from the stomach to the vent. Ps 
The testes and ovaria are identical in character, position and relations with those of the 
foregoing Ascidian. 
The heart lies on the left side of the body, just below and in front of the corresponding 
ovarium. It rests on a small brown cylindroid body with rounded extremities, and 
exhibiting a slight curvature, with its concavity looking upwards and forwards. This 
body appears to lie loosely in a blood-sinus adapted to receive it, and is chiefly composed 
of minute cells, cell-nuclei, and an amorphous matter enclosed in a membranous sace, 
but exhibiting no very definite arrangement. What its real nature is I have not been 
able to determine, though I am disposed to believe that it may be the representative of 
the * elæoblast” of the Salpian, 
III. In Shark Bay also, and in about three fathoms water, we obtained another small 
Ascidian, so nearly allied to those just described as to merit brief notice here. It is nearly 
of the same size as the King George’s Sound species, but rather more narrowed and pro- 
duced above, and more rounded at the base. | 
The branchial and cloacal openings lie on nearly the same level, at the extremes of the 
upper border, and are tubular and prominent, though capable of considerable retraction. 
— The test is thin, smooth, colourless, and beautifully transparent, s0 far calling to mind 
the pelagic Tunicata generally. It is, however, loosely covered over with the fine sandy 
Particles of the sea-bottom on which it rests, being apparently quite unattached, though 
Perhaps unable to change its place at will. 
- The muscular coat id its epithelial covering are also quite transparent and free trom 
Pigment. : «ie : 
The external openings, particularly at their base, are surrounded with pue: an 
VOL. xxıı, i 
