NoTT. — On N.Z. Composite Ascidians. 321 



small section of the distal extremity somewhat transparent, 

 and the connecting tube is always small, and only slightly 

 stained. My first thought was that here we had a commenc- 

 ing bud. But no traces of indubitable gemmation were dis- 

 covered ; and, moreover, even in young zooids, which had not 

 reached the surface of the colony, these bodies were just as 

 large and distinct as in the adult. In fact, they seem never 

 to change. Their constancy throughout the whole of my 

 sections, moreover, seemed to render this view untenable. 



Were they highly-developed vascular appendages ? This, 

 again, seemed unlikely, for they are in all cases present only 

 in the middle layer of the test, where the numerous zooids 

 rendered unnecessary any such highly-developed vessels, 

 while the lower layer, in which such prolongations usually 

 terminate, was left vacant. Moreover, they spring from the 

 side and not from the ventral surface as is more usual (c/. 

 preceding descriptions). 



Possibly it may represent a brood-pouch : but in that 

 case its walls must be remarkably glandular ; and its position 

 is, moreover, peculiar if such be its function. In any case, no 

 traces of ova were observed within. 



For the present, then, I must leave this organ unexplained. 

 That it has some special function of importance can scarcely 

 be doubted ; and its glandular nature, combined with its con- 

 nection only with the mantle, to a certain extent may justify 

 the term "vascular appendage " which I have applied to it in 

 my plate, and which I retain, very unwillingly, for its pro- 

 visional appellation. 



Polysyncraton fusciim, n. sp. Plate XXIX. 



Numerous colonies of very large extent were obtained in 

 September. 



Corm thin, fleshy and incrusting, uniform in thickness, 

 varying from l-5mm. to 2mm. Colour varies from deep 

 reddish-brown to nearly black, the former colour on the whole 

 predominating. The zooids are moderately conspicuous in 

 position, owing to the semi-transparent nature of the test : 

 they are not arranged in regular systems. 



The branchial pores are small and not easy to distinguish : 

 still, during life they may be discerned with a little care. 

 The common cloacal openings, on the other hand, are very 

 distinct, the transparent colourless outer layer' of the test 

 being raised up around them in such a way as to render them 

 easily conspicuous. This is further aided by the cloacal 

 canals, which ramify in all directions, as may readily be seen 

 by the large yellow fgecal pellets within (fig. 2, c.e. and c.c.o.). 



A few spicules are present, being met with only around 

 the zooids (fig. 2). They vary extremely in size (fig. 4), but 

 21 



