80 THE AUSTRALIAN MUSEUM. 



f 



Polyclinum globosum, n. sp., PI. Pel. II., figs. 38. 



External appearance. The shape of the colony is like that of many 

 Fungi, and consists of a short and very stout peduncle, bearing a 

 massive dome-shaped Ascidiarium. The Ascidiarium has its length, 

 breadth, and thickness about equal. Its top is convex, and not pointed. 

 It is of greyish white colour, and is fairly hard and elastic. The 

 peduncle is covered externally with sand grains (fig. 3). It is of a very 

 dark grey colour, and is about twice as thick as its length. The 

 dimensions are as follows: Length of Ascidiarium 5'3 cm., breadth 

 5 - 5 cm., thickness 5'0 cm. Length of peduncle 2-7 cm., thickness 

 3 to 5 cm. 



The Ascidiozooids have retracted about 5 mm. from the surface 

 (fig. 4). They measure 1-2 cm. in length and 1-5 mm. in breadth. 

 The abdomen is twice or two and a half times the length of the thorax 

 (fig. 5). The vascular appendages are filled with blood corpuscles, and 

 are budding. Numerous tailed larvae and embryos are to be found in 

 the incubatory pouches. The average length of the tailed larva is 1 mm., 

 and the breadth at the broadest end is - 67 mm. (see fig. 8). 



The test contains many bladder cells with fusiform nuclei. There 

 are rather large test cells, but no pigment cells. 



The mantle is exceedingly thick and strong, and is much contracted. 

 It has longitudinal muscle bands (of two fibres each) running with 

 regularity over the branchial sac and bifurcating at the branchial 

 sphincter. 



The branchial sac is very much corrugated and obscured by the 

 contraction of the mantle. The longitudinal vessels are wider than the 

 stigmata (fig. 7), w r hich are about nine or ten times as long as wide. 

 There are 8 transverse vessels in the branchial sac. 



The dorsal lamina is represented by a series of small, tentacular 

 languets, placed about their own length apart (fig. 6). 



The tentacles are rather short and stiff. There are 8 or 10, all of the 

 same size. 



The alimentary canal is a long, simple loop, like that of the last few 

 species, having a thick-walled oesophagus, and a thin-walled intestine ; 

 while there is a simple ovate stomach placed posteriorly. The rectum 

 only reaches the posterior end of the thorax (fig. 5). 



The reproductive organs lie in the intestinal loop. Ova, spermatic 

 vesicles, and tailed larvas are all present in the same Ascidiozooids. 



Locality. Port Jackson ; three colonies. 



