76 
THE VOYAGE OF H.M.S. CHALLENGER. 
osculis numerosissimis, luteis, lineatis.” Then follows a short paragraph of remarks 
containing nothing of importance. The specimens were found at King George’s Sound 
and Port Western in the south of Australia. 
On the whole there can be little doubt that this is our species. The differences in 
shape and arrangement of the Ascidiozooids are slight, and it has been seen that there 
is a certain amount of variation in these particulars among the Challenger specimens 
themselves. The appearance of blue in the “ Astrolabe ” specimen is more puzzling, 
but is not, I think, sufficient to separate the two forms. In ours the shades of grey, 
yellow, and brown vary considerably, and the “ Astrolabe ” one may have been 
abnormally coloured. It must also be remembered that the Challenger specimens have been 
in spirit for some years. The figure showing the lobed apertures with such wonderful 
distinctness and regularity may perhaps have been taken from the living animal, certainly 
nothing so perfectly regular is visible in the apertures of the Challenger specimens. 
The only other reference to this species I can find is in the report on the animals 
obtained during the cruise of the “Nassau.”^ Professor E. 0. Cunningham there 
reports from the Strait of Magellan, “ Aplidium pedunculatum, Quoy and Gaimard, 
attached to Macrocystis.” 
During the Challenger Expedition this species was taken at six localities, viz., 
(] ) at Station 313, at the eastern end of the Strait of Magellan, from a depth of 55 
fathoms (five specimens) ; (2) at Kerguelen Island, 20 to 60 fathoms (one specimen) ; 
(3) at Kerguelen Island, 10 to 60 fathoms (three specimens) ; (4) at Station 151, 
south-west of Heard Island, 75 fathoms (1 specimen); (5) at Station 315, on the east 
coast of the Falkland Islands, 12 fathoms (1 specimen); and (6) at Station 314, between 
the Strait of Magellan and the Falkland Islands (2 specimens). 
An examination of the external features alone of this form suffices to show that it 
does not belong to the genus Aplidium, as stated by Quoy and Gaimard and later by 
Cunningham, or even to the family Polyclinidse ; while the dissecting out of one of the 
Ascidiozooids from the common test shows that it is a member of the Distomidse, but 
differs somewhat from the recognised genera. It is found, however, to agree in all 
essential particulars with the new and remarkable species Colella thomsoni and the 
other members of the same genus, to be described further on, and consequently the 
present species must be placed in the new genus Colella. Quoy and Gaimard’s specific 
name pedunculatum is retained. It must be remembered, however, that the name was 
given when the species was supposed to be an Aplidium, and that the possession of a 
peduncle is a character common to all the species of Colella. As the animal had never 
been properly examined, I have submitted it to a detailed investigation, and, as it has 
some interesting peculiarities, an account is inserted here of the anatomy and histology 
for comparison with the detailed description of Colella thomsoni which will follow (p. 94). 
* Tram. Linn. Soc. Lond., vol. xxvii. p. 490. 
