CATALOGUE OP TUNICATA. 63 



peduncle. The length of the Ascidiozooids is about 2 mm., and the 

 breadth O5 mm. The thorax and abdomen are about equal in size, 

 but separated by a considerable constriction formed of oesophagus and 

 rectum. There is an incubatory pouch and a vascular ectodermal 

 appendage. 



The test is soft and smooth and glistening, and of a whitish colour 

 on the upper part of the body. In the peduncle it is tougher and of a 

 darker colour, but still smooth. The matrix is clear and structureless, 

 and contains stellate and fusiform test cells. A few white pigmented 

 cells and bladder cells are scattered through the test of the upper part of 

 the body ; while in the peduncle there are no bladder cells, but the test 

 is very much cut up by the numerous longitudinally running canals, in 

 which the vascular appendages are placed. 



The mantle is moderately developed. The muscle bands runs longi- 

 tudinally. 



The branchial sac contains 3 rows (occasionally 4) of stigmata, with 

 about 10 in each row, on each side ; so there are about 60 stigmata 

 altogether. They are very large and closely placed. 



The endostyle is very distinct, and has an undulating course. It 

 projects slightly beyond the branchial sac at the posterior end. 



The dorsal languets are very short. 



The tentacles are 10 in number, 5 large and 5 small, placed alternately. 



The dorsal tubercle is a simple circular opening. 



The viscera form an ovate mass attached to the branchial sac by a 

 long narrow peduncle. The stomach is of an elongated pyriform shape. 

 The intestine is long and narrow. The reproductive organs lie in the 

 loop of the intestine. 



Locality. Port Jackson. 



There are about 27 specimens of this very remarkable species, which 

 may possibly be the Aplidium cerebriforme of Quoy and Gaimard. In 

 the largest specimen the peduncle is 7'4 cm. in length and 2-2 cm. in 

 diameter, while the greatly-expanded upper part of the body is over 43 

 cm. in horizontal extent following all the folds. It is only 1-1 cm. in 

 vertical extent and 7 mm. in thickness. The chief point in which the 

 measurements of specimens differ is the horizontal extent of the body, 

 which in the smallest specimen is only 5'5 cm. The peduncle shows all 

 stages between a perfectly simple columnar and a very much sub- 

 divided tree-like condition. In some of the branched specimens the 

 intervals between the branches are open, but in most cases they are 

 filled up by a thin membrane-like layer of test. 



