92 THE AUSTRALIAN MUSEUM. 



Tentacles 8, with the 2 lateral ones larger than the other 6. 



Dorsal tubercle with a simple oval opening. 



Alimentary canal with a thick-walled oesophagus, leading to an oval, 

 smooth-walled stomach. Pylorus narrow, intestine widens, runs along 

 ventral edge of stomach, and then crosses oesophagus to become the 

 thin-walled rectum (fig. 6). 



Gonads. Masses of spermatic vesicles, with thick spiral vas deferens 

 and a few ova. 



Locality. Port Jackson. One large and one small colony, apparently 

 attached to a piece of wood (? part of a pier). 



Leptoclinum patulum, n. sp., PI. Did. II., figs. 712. 



Colony large, flat, expanded over the test of a large Simple Ascidian ; 

 of a white colour, marbled over the surface with a network of grey-blue 

 veins, which follow for the most part the course of the common cloacal 

 cavities (fig. 7). Length of the colony, 8 cm. ; breadth, 5 cm. 



Test containing numerous calcareous spicules, which are larger but 

 not nearly so numerous as in the case of Leptoclinum incanum. The 

 test, for a short way round the branchial aperture, is almost free from 

 spicules (fig. 9). There are many small circular and fusiform test cells 

 (fig. 11). Occasional stellate cloacal apertures (fig. 8) are present. 



Ascidiozooids arranged in lines alongside the branches of the common 

 cloacal cavities. Body divided into thorax and abdomen. 



Mantle with strong branchial sphincters, and longitudinal muscle 

 bundles over thorax and abdomen. 



Branchial sac with 4 row r s of rather long, narrow stigmata (fig. 10). 

 Muscles in the transverse vessels. 



Dorsal lamina represented by a short, thick languet on each trans- 

 verse vessel. 



Tentacles 10. In some very minute intermediate ones also occur. 



Dorsal tubercle with a small, circular opening. 



Alimentary canal and gonads as usual, stomach globular (fig. 12). No 

 larvae were seen. 



[The following Didemnidae have also been recorded from Australian 

 seas : 



Didcmnum aurantiacum. Herdm., Bass Str. 

 Leptoclinum Jacksoni, Herdm., Port Jackson. 

 L. psammathodes, Sluiter, Thursday Is. 

 L. pantherinum, Sluiter, Amboina. 



