82 THE AUSTRALIAN MUSEUM. 



The reproductive organs, both ova and spermatic vesicles, lie in the 

 short, stout post-abdomen behind the intestinal loop. 



Locality. Port Jackson. A single colony attached to the carapace 

 of a Dromia, 1882. 



Polyclinum fuscum, n. sp., PI. Pel. III., figs. 1 6. 



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

 supporting a globular, massive Ascidiarium. The single colony is im- 

 perfect, about one-third, at least, of the head having been cut off. The 

 whole colony is of a dark brown colour. The peduncle is encrusted with 

 dark yellowish brown sand and shell fragments, &c. The lower 3 cm. of 

 the Ascidiarium has no apertures of Ascidiozooids in it, but is smooth 

 test externally. This region is partly encrusted with foreign bodies. The 

 dimensions are: Length of Ascidiarium 10 cm., breadth probably 10 to 

 12 cm., thickness 6'5 cm. Length of peduncle 3 - 5 cm., breadth 7 cm., 

 thickness 3 - 5 cm. 



The Ascidiozooids are all slightly retracted, but are not more than 

 5 mm. from the surface. They are closely placed all over the surface, 

 except in the basal 3 cm. They are very long, varying from l - 5 to 2 - 5 

 cm., antero-posteriorly ; of this the thorax is 3 or 4 mm. only. An 

 incubatory pouch is present, containing about 4 tailed larvae (fig. 2). 



The test contains bladder cells and many brown pigment cells (fig. 3). 

 The test cells are few and small. There are also numerous crystals, 

 which are probably due to post-mortem changes. 



The mantle is delicate, and is not pigmented. The muscle bands of 

 the thorax run longitudinally only. 



The branchial sac is long and rather narrow. The stigmata are long 

 and narrow, being about eight or nine times as long as wide (fig. 4). The 

 branchial sac is rather corrugated and opaque. There are about 12 rows 

 of stigmata. 



The dorsal lamina is represented by about 12 languets, which are set 

 three-quarters of the length apart. Each is about 0'2 or 0'3 mm. in 

 length and rather stout (fig. 5). 



The tentacles are 24 in number. There is one very large tentacle and 

 5 others on a level with it ; while further back, and alternating with 

 these 6, are 6 others of about the same size as the 5 first ; then still 

 further back are 12 very small and stiff tentacles, alternating with the 

 other 12 (see fig. 6). 



The alimentary canal forms a long, narrow loop four or five times as 

 long as the branchial sac. The stomach is simple. The intestine only 

 reaches a very short way up the thorax. 



