CATALOGUE OF TUNICATA. 77 



stigmata, and about 40 in a row on each side. The stigmata are fairly 

 wide, but are seven times as long as wide (fig. 13). They are rather 

 wider than the thickness of the inter-stigmatic vessels. The transverse 

 vessels bear narrow horizontal membranes. 



The dorsal lamina is represented by about 10 closely-placed languets 

 (fig. 12), with large out-spreading bases, and reaching a length of 

 about - 3 mm. 



The tentacles are all similar. There are about a dozen. 



The alimentary canal has a very long and narrow oesophagus, which 

 enters a heart-shaped stomach at its wider end (fig. 14). The stomach 

 has 4 longitudinal folds in all. The posterior end of the stomach passes 

 by a narrow constriction into the intestine, which widens again suddenly. 

 The intestine runs posteriorly, and then at its most posterior point it, 

 in some cases, widens again slightly. It then turns anteriorly, and 

 becomes narrow for some distance, and then finally swells into the wide, 

 thin-walled rectum, which runs up the dorsal edge of the thorax. The 

 gland running over the intestine (fig. 15) is unusually large, and can be 

 clearly seen with a 1 in. objective. Its duct seems wide and flattened, 

 or ribbon-shaped. 



The reproductive organs are not present in all Ascidiozooids. When 

 present, the post-abdomen is filled with spermatic vesicles up to the 

 bend of the intestine. The masses have a polygonal shape, and fit 

 closely side by side so as to form a long sausage-like mass. 



Locality. I have one colony of this species from Sydney harbour. 



The branched vascular appendages in the test are in a particularly 

 interesting condition. They show an intermediate state between the 

 straight unbranched vascular appendages of the Distomidae (e.g., Colella) 

 and the branched anastomosing vessels of the Botryllidae ; while, from 

 the presence of a post-abdomen, the species clearly belongs to the Poly- 

 clinidae. It may possibly be the form alluded to, but not fully described, 

 by Macdonald under the name of " Polyclinoides " a name which has 

 been proposed several times over by various authors. 



Polyclinum, Sav., 1816. 



I place the following seven species, which seem to be undescribed, in 

 this genus, chiefly on account of the stomach walls not showing any 

 grooves or thickenings. 



Polyclinum clava, n. sp., PI. Pel. I., figs. 58. 



External appearance. The colony consists of an ovate Ascidiarium 

 borne on a stout peduncle, which tapers downwards to a narrow base of 



