CATALOGUE OP TUNICATA. 79 



Polyclinum giganteum, n. sp., PL Pel. II., figs. 1 and 2. 



External appearance. The colony consists of a short, thick peduncle, 

 bearing a pyriform or ovate massive Ascidiarium. The peduncle narrows 

 to its point of attachment, and is of a darker grey than the upper part of 

 the colony. It is slightly encrusted with sand on its surface. The colour 

 of the Ascidiarium is a light yellowish grey. Its consistency is soft and 

 spongy, and it is readily deformed (fig. 1). The dimensions are as 

 follows: Length of Ascidiarium 7cm., breadth 4-5 cm., thickness 3'3 

 cm. Length of peduncle 3 - 5 cm., thickness 2 cm. 



The Ascidiozooids are not much retracted. They are scattered over 

 the surface. Each is about 6 mm. in length and 2 mm. in breadth. The 

 abdomen is twice as long as the thorax. The vascular appendages are 

 very long, and some have buds. 



The test is rather firmer on the outside than inside. The small test 

 cells are spherical, fusiform, and stellate. There are no pigment cells, 

 and very few bladder cells. 



The mantle is strong and rather contracted on the thorax. It has 

 longitudinal muscle bands (formed of two fibres each), which run with 

 regularity over the thorax. 



The branchial sac is very opaque and corrugated, being thrown into 

 folds and obscured by the contracted state of the mantle. The stigmata 

 are about 8 or 9 times as long as broad. 



The dorsal lamina is represented by a large number of short and 

 very closely-placed languets. 



The tentacles are about 20 in number, and are of 2 sizes, placed 

 alternately. 



The dorsal tubercle has a simple circular or oval opening. 



The alimentari/ canal forms a narrow loop. The thick - walled 

 oesophagus passes back to the posteriorly-placed simple stomach, from 

 which the delicate intestine runs anteriorly and dorsally, to end about 

 one-third of the way up the thorax. 



The reproductive organs lie in the intestinal loop. The spermatic 

 vesicles axe numerous, and closely placed. 



Locality. Port Jackson ; two colonies. 



The larger colony (fig. 2) measures 11 cm. by 9 cm. by 4 cm. The 

 figure represents it nearly natural size. The other colony (fig. 1) is 

 smaller, and has the anterior ends of the Ascidiozooids more distinctly 

 marked. 



