136 
THE VOYAGE OE H.M.S. CHALLENGER. 
are developed in the test (PL XIX. fig. 7). These peculiar spicules are described more 
fully in the account of the species given below, but they seem very similar in all the 
five known species, and are quite unlike any other form of spicule found in the Tunicata. 
The test is always more or less cartilaginous in consistence, and contains large 
numbers of bladder cells. The mantle is moderately strong, and the branchial and 
atrial siphons are both of good size and are six-lobed at their openings. The atrial siphon 
apparently may vary considerably in form. Von Drasche states that the shape differs in 
different specimens of Cystodytes durus, and the forms I have figured (PI. XIX. fig. 11, aL, 
and PL XX. fig. 7, at.) for Cystodytes draschii and Cystodytes philippinensis are very 
dissimilar. Common cloacal apertures are always present. 
The stigmata in the branchial sac are always of rather small size, and are not very 
numerous. The tentacles, so far as is known (they are not described by von Drasche), 
are exceptionally long and numerous. The stomach is always smooth walled. The 
reproductive organs are hermaphrodite. 
The five known species of Cystodytes, though agreeing in all the above characters, 
may, I think, be readily distinguished. In colour they differ considerably. Cystodytes 
dellecliiaicB is violet, Cystodytes durus is of a distinct yellow colour, Cystodytes cretaceus 
is milk-white, Cystodytes draschii is of a brownish-grey, and Cystodytes philippinensis 
is rather darker than the last. Cystodytes durus and Cystodytes cretaceus form decidedly 
thicker colonies than Cystodytes draschii and Cystodytes philippinensis. Cystodytes 
durus and Cystodytes cretaceus have the Ascidiozooids arranged in distinct systems, arid, 
judging from von Drasche’s figures, this is especially the case in Cystodytes durus, where 
the systems are obvious and very clearly circumscribed. In the two new species no such 
distinct arrangement is found, and in Cystodytes dellechiaice, according to Della Valle, the 
systems are not well-marked. On the whole the new species are nearer to one another 
than to any of those previously known, which are very clearly distinguishable by their 
colours (see von Drasche’s beautiful plates). The detailed comparison of the two new 
species will be given below under Cystodytes philippinensis. 
The five species may briefly be distinguished by the following characters : — 
.1 
Ascidiozooids arranged 
in distinct systems. 
i 
1 1 
Colour yellow. Colour white. 
Cystodytes. 
1 
1 
Ascidiozooids not 
distinctly arranged in 
systems. 
1 
1 1 
Colour violet. 
Colour hrowuish-grey. 
Colour dark brownish- 
C. durus. C. cretaceus. 
1 
Test not much 
grey. Test very much 
C. dellechiaice. 
vacuolated. 
vacuolated. 
C. draschii. 
G. philippinensis. 
