REPORT ON THE TUNICATA. 27 



Savigny ' distinguishes three varieties in this species : — 



(a) Body having, both externally and internally, a strong brown tint, which 



appears to be due to a brown matter which fills the branchial cavity. The 

 terminal papillas are large, and for the most part obtuse. The diaphragm is 

 very narrow, and leaves a large aperture. Total length, 13 to 14 inches. 



(b) Body bluish or slightly violet, perfectly diaphanous. The papillae are rather 



narrow. There is no ring-like diaphragm at the aperture, which is surrounded 

 only by very young Ascidiozooids. Total length, G inches. 



(c) Body bluish, perfectly diaphanous. The papillae are longer and more pointed 



than in the preceding varieties. The ring-like diaphragm leaves only a very 

 narrow opening, which is surrounded by Ascidiozooids nearly all of which are 

 adult. Total length, 3, G, 7 inches. 



Of these varieties the Challenger specimen from off Cape Verde most nearly 

 resembles the last (var. c). 



The test in this specimen is very richly provided with test cells. In the surface 

 layers they are especially numerous, and are nearly all greatly elongated and arranged 

 so as to be nearly parallel to one another. Here and there a stellate or a large round 

 granular cell is to be found (PI. I. fig. 5). In the deeper parts of the test between the 

 Ascidiozooids, the cells are not so numerous and are nearly all stellate, with very long 

 branched processes (PI. I. fig. G). Here also some of the large round granular cells are 

 present. At the branchial aperture, as iu other Tunicata, the test is turned in to line 

 the branchial siphon. In this inflected part of the test (PI. I. fig. 7) the cells are few 

 and small, but in the test outside the branchial aperture, and just above the sphincter 

 muscle, a very large number of small rounded cells are present. 



The Challenger Expedition also obtained six specimens (probably from near the 

 surface) in the Antarctic Ocean, to the south of Australia, which I refer to the present 

 species. They are from Station 159, March 10, 1874, lat. 47° 25' 0" R., long. 130" 

 22' 0" E., surface temperature 51°"5, bottom temperature 34'''5, and were captured in 

 the trawl, which had been down to a depth of 2150 fiithoms. They are all of large 

 size, but some are incomplete. The dimensions of the largest are as follows : — ° 



Total length, 

 Breadth at oiDcn end. 

 Breadth at widest point, 



„ closed end, 



Diameter of common cloacal aperture, 

 Thickness of colony (from outside to inside), 



1 Systeme des Ascidies, p. 207. 



- One of the fragments, however, must have belonged to a much larger specimen, as it is 7 cm. in breadth, and has 

 the common cloacal aperture 4'5 cm. iu diameter. 



