1915.] A. Oxa: The Tunicata of the Indian Museum. Jo 
The ovaries, of which we find likewise one on each side, are elongated tubular organs 
placed for the greater part horizontally in the same level with the testes and in direct 
contact with the dorsal part of these organs. Each ovary is bent almost at a right 
angle near its distal end, so that the terminal portion assumes a vertical position. 
This part is pointed anteriorly and is directly continuous with the oviduct. The 
latter is short and wide and opens with a large gaping aperture into the cloacal cavi- 
ty at the base of the atrial siphon. The axial portion of the ovary is taken up by a 
spacious canal directly continuous with the oviduct, while the ova are found imbed- 
ded in, or bulging out of, the thickness of the wall. 
The Excretory Organ is globular in shape, and is situated just inside the mantle 
on the ventral median line of the trunk. It is a large, completely closed, sac-like 
organ with thin transparent membranous walls, in which a comparatively large dark 
brown spherical concretion is seen floating. 
Locality.—South of Ceylon, at Station 278; 6° 52’ N., 81° 11’ E.; depth 1912 
fathoms, bottom green mud and sand, January 11, 1901. Five specimens. 
The genus Hexacrobylus, undoubtedly the most extraordinary member of the 
Order Ascidiacea, has hitherto been known to science in only one species, namely, 
H. psammatodes, Sluiter (13, 14). A single specimen of this form was collected 
during the Siboga-Expedition at Station 211 (5° 40’ 7” S., 140° 45’ 5” E.) from a depth 
of 1158 meters, and a detailed account of its external appearance and its internal ana- 
tomy, so far as could be ascertained from the unique specimen, was given by Sluiter 
in 1005 in the Report of that Expedition. As the present species differs markedly 
from this form in some essential points of structure, it will be interesting to go over 
the more important organs and examine the differences and resemblances which they 
exhibit in these two forms. 
In regard to the external form, the difference between the two species appears to 
be considerable. In H. psammatodes the body is provided at the anterior end with a 
distinct collar, sharply bounded from the trunk proper and a little narrower than the 
latter. The trunk proper is cylindrical in shape and bears a small tail-like atrial 
siphon at the posterior end. Thus, in this species, the branchial and atrial apertures 
lie at the anterior and posterior extremities of the body, whereas in the new species 
here described the branchial aperture is on the ventral edge and the atrial on the an- 
terior surface, so that the two apertures are separated only by a fraction of the longi- 
tudinal circumference of the body. However, this difference might be more apparent 
than real, since the condition met with in H. psammatodes would also be produced in 
H. indicus if the atrial aperture were shifted dorsally until it came to lie opposite the 
branchial, and the denominations of parts were changed accordingly. The condition 
of the external surface and the colour of the animal seem to be essentially the same 
in both forms. 
In H. psammatodes the test is very thin, especially on the ventral side, but on the 
tentacle-like lobes of the branchial aperture it is thicker and brittle on account of 
foreign bodies imbedded in its substance. In H. indicus, on the contrary, the test 
is rather thick all over, and is elastic and never brittle. The delicate hair-like 
