70 THE AUSTRALIAN MUSEUM. 



mata (fig. 4), about fourteen to sixteen times as long as broad. The sac 

 is produced ventrally into an endostylic prolongation, and the dorsal 

 edge is only about half as long as the ventral (fig 3). There are altogether 

 about 20 stigmata on each side of the branchial sac. 



The dorsal lamina is represented by a few very long languets, which 

 are wide at the base and taper rapidly (fig. 5). 



The tentacles are 24 in number, and are of three distinct sizes, arranged 

 alternately (fig. 6). Of the six long ones, 3 are a little longer than the 

 others, and one of these 3 (placed laterally) is longer than its fellows. 

 The 6 medium-sized are very much shorter than the 6 long, and vary a 

 little amongst themselves in size and shape. The 12 short tentacles are 

 exceedingly short, being mere papillae (fig. 6). The 6 long tentacles 

 spring from a line a little posterior to the insertion of the others. The 

 tentacles are pigmented. 



The alimentary canal is a simple U-shaped loop, which, from the 

 great ventral prolongation of the branchial sac, appears to arise half-way 

 along the dorsal edge of the thorax. The oesophagus is wide, but narrows 

 before passing into the oval stomach. The intestine is wide and rather 

 thick-walled. It contained, in the specimen examined, a very large 

 number of parasitic Gregarinida. 



There are no reproductive organs in the intestinal loop. 



Locality. Port Jackson. 



Two colonies of this remarkable blue species were found in the collec- 

 tion, labelled Sigillina aitstralis, Savigny. They differ, however, very 

 markedly from the description and figures given by Savigny, and even if 

 Savigny's Sigillina turns out to have been one of the Distomidae, which 

 is not likely, still it must be regarded as at least specifically distinct from 

 the present form. Savigny gives the colour of his form as being yellowish 

 green, while in the present specimen it is a very dark blue. Then, again, 

 the form of the Ascidiozooids and the branchial sacs differ. I can find 

 no trace of a post-abdomen in these specimens, and so place the species 

 in the present family. At first I was inclined to regard the form as a 

 Polyclinid. 



[The following Uistomidte have also been described from Australian 

 Beas : 



Colella pcchmculata, Q. and G., Port Western. 



C. pulchra, Herdm., Torres Str. 



C. clongata, Herdm., P. Jackson. 



C. Murray!, Herdm., S.E. Australia and Port Jackson. 



