KEPOET OX THE THXICATA. 
141 
broken up by the presence of innumerable bladder cells which in most places are so 
abundant as to become polygonal by mutual pressure, and reduce the matrix to a system 
of mere bands and membranes separating the cavities from one another. The usual small 
variously shaped cells are abundant all through the test. In the neighbourhood of the 
Ascidiozooids are found the large discoid spicules which form the calcareous covering. 
The Mantle is strong and has a well-developed musculature. The muscle fibres are 
large and numerous, and form a close network. They run in all directions. 
The Branchial Sac is small and thick walled. The transverse vessels are wide and 
aU of one size. The stio-mata are rather small. The fine longitudinal vessels are 
narrower than the stigmata. 
The Tentacles are numerous and rather long. 
Locality. — Samboangan ; depth, 10 fathoms. 
Of this species of Cystodytes three small colonies were obtained olf Samboangan in the 
Philippine Islands, from a depth of 1 0 fathoms. It is closely allied to the last described 
species, but they differ in a number of details which are pointed out below. 
Like Cystodytes draschii this is a flat or nearly flat expanded incrusting colony, which 
is probably attached to foreign objects by the greater part of its lower surface. It is of 
quite irregular shape (PI. XX. figs. 1, 2), and grows out into rounded lobes. The margin 
is thick and projecting as in the last species, but it is more irregular and not so trans- 
parent. A slight expanded thin margin is present at one or two points. The upper 
surface is undulating, and has besides numerous very slight elevations which correspond 
to the anterior ends of the Ascidiozooids. It is smooth and somewhat glistening, but 
not so much so as in the case of Cystodytes draschii. The lower surface (PI. XX. fig. 2), 
on the contrary, is not so rough as in the previous species. It is, however, very irregular, 
and has various foreign bodies — sand-grains, shell fragments, and Polyzoa — adhering to 
it. There is a slight rounded margin, varying from 2 mm. to 5 mm. in thickness, round 
the greater part of the edge (PI. XX. fig. 2), which evidently did not adhere. 
The colour is distinctly duller and darker than in Cystodytes draschii, and has none of 
the yellowish tinge found in that species, otherwise it is similar. The Ascidiozooids 
show through in the same indistinct manner (PI. XX . figs. 1, 2), but form smaller light- 
coloured areas than in the previous species. The under surface is scarcely at all lighter 
in colour than the upper, and the Ascidiozooids do not show through so distinctly on 
this surface. In short the Ascidiozooids altogether are rather less conspicuous in this 
species than in the last. 
In a section the Ascidiozooids are seen to be mostly placed vertically in the colony 
(PI. XX. fig. 3); some, however, are inclined. No arrangement in systems can be 
distinctly made out. The general shape of the Ascidiozooid and its relation to the 
surrounding calcareous capsule (PI. XX. figs. 3, 5) is the same as in Cystodytes draschii. 
