72 THE AUSTRALIAN MUSEUM. 



great part covered with sand grains, shell fragments, worm tubes, and 

 other adhering foreign bodies. The lower end of the peduncle is attached 

 by a wide surface. The Ascidiarium is firm, light grey in colour, and 

 fairly transparent. On account of the retraction of the Ascidiozooids, its 

 sm-face is pitted all over. The dimensions are : length of Ascidiarium 

 5 cm., breadth 8'5 cm., thickness 48 cm. Length of peduncle 3 - 5 cm., 

 thickness 4'2 cm. 



The Ascidiozooids are irregularly placed. They are very long (PI. 

 Pel. I., fig. 4), being about 2 cm. antero-posteriorly. The body is divided 

 into thorax and abdomen, with a long vascular appendage. The thorax 

 in the contracted state is only half the length of the abdomen, and is of 

 a clear white colour, with a dark streak along the dorsal edge, caused by 

 the rectum, and regular longitudinal lines which indicate the muscle 

 bands. In some cases the thorax is greatly distended with developing 

 embryos. No tailed larvae were seen. 



The, test is firm and cartilaginous. It has no pigment cells. The test 

 cells are large and stellate or spherical. Bladder cells are also present. 



The -mantle is not very delicate, and is moderately muscular. Longi- 

 tudinal muscle bands run at regular intervals over the thorax, and each 

 bifurcates as it approaches the branchial aperture. There are about 20 

 of these longitudinal muscle bands. At the posterior end of the thorax 

 they converge ventrally and dorsally to form two very powerful muscles, 

 which run posteriorly over the abdomen. 



The branchial sac is rather wide. It has about 12 rows, of about 40 

 stigmata in each row. The stigmata are moderately long, and are 

 regular. The transverse vessels are strong, and have horizontal mem- 

 branes attached to their inner edges (PI. Pel. I., fig. 2). 



The dorsal lamina is represented by a series of exceedingly long and 

 closely-placed languets (PL Pel. I., fig. 3), each being at least 0"5 mm. 

 long. There are about 20. They taper from a very wide base to a fine 

 point, and are covered with large cilia. 



The tentacles are 24 in number, and are of two sizes, placed alternately. 

 The larger ones vary in size. 



The alimentary canal forms a very long, narrow U-shaped loop. The 

 very long oesophagus runs back to a posteriorly-placed stomach, from 

 which the long, thin-walled intestine passes forwards, to end near the 

 atrial aperture. The stomach wall is folded longitudinally. 



The reproductive organs lie in the intestinal loop, and extend a little 

 beyond it posteriorly. 



Locality. One colony of this species was in the collection from Port 

 Jackson. 



