86 THE AUSTEALIAN MUSEUM. 



branches ending in rounded knobs (fig. 6) ; attached by a small but flat 

 and slightly expanded base (fig. 7). Ascidiozooids visible on surface, but 

 no arrangement in systems seen. Surface closely encrusted with sand 

 grains all over. Colour sandy grey. Length about 13 cm., breadth of 

 colony about 4 cm., thickness of a branch about - 5 cm. 



Test not very brittle, but containing much imbedded and encrusting 

 foreign matter, so as to be perfectly opaque. Outer layer of test rather 

 firmer than the rest. No bladder cells, no pigment cells, and no vessels 

 visible. Small test cells numerous (fig. 10). 



Ascidiozooids about 3 mm. long. Thorax about 1 mm, abdomen 

 longer, and post-abdomen very short (fig. 8). 



Mantle rather corrugated and opaque, both longitudinal and trans- 

 verse muscle bundles are present. 



Branchial sac with about 8 rows of stigmata. Stigmata narrow, 

 much narrower than the inter-stigmatic vessels. Transverse vessels 

 moderately wide, and containing muscle fibres (fig 11). 



Endostyle conspicuous and convoluted. 



Dorsal lamina represented by a number of closely-set languets. They 

 are rather large and widen at their bases (fig. 9). 



Tentacles 10 or 12, of two sizes, placed alternately. 



Alimentary canal with a short oesophagus leading to an oval, opaque, 

 smooth-walled stomach (fig. 8). Intestine narrow, rectum wider, and 

 full of black faecal pellets. 



Gonads consisting of a mass of spermatic vesicles. No ova w y ere 

 seen ; but the peribranchial cavity contained many tailed larvae, which 

 rather points to a protogynous condition. The larva has rather a 

 short tail, three adhering papillae in front, and a single plano-convex 

 black sense organ placed far back in the body (fig. 12). 



Locality. Port Jackson ; several colonies and fragments. 



Psammaplidium fragile, Herdman,* PI. Pel. VI., figs. 1014. 



Colony massive, being an irregularly-lobed, rather brittle mass (fig. 10), 

 closely encrusted and permeated with sand, except in the centre. Ascidio- 

 zooids visible on the surface, but not in systems, and no common cloacal 

 cavities seen. Surface irregular, but rather smooth. Colour sandy grey. 

 Length 10 cm., breadth 4 cm., thickness from 5 mm. to 10 mm. 



Test. A narrow axial band of test in the centre of the colony, and 

 posterior to the bodies of the Ascidiozooids, contains scarcely any sand, 

 and is of a dark bluish grey colour (fig. 11). No pigment cells, bladder 



* "Revision," 1891, p. 620. 



