10 MK. A. W. "WATEE3 OK BRTOZOA FEOM BAPALLO 



C. Darwinii, Busk, dredged by the ' Challenger ' from 

 Nightingale Island, is very similar to the European G. Boryi, 

 as the vibracular chambers are identical in shape, so are the 

 avicularia both lateral and median. The character by which the 

 two species are distinguished is that in G. Boryi there is a cal- 

 careous bar belovv the proximal border of the oral aperture, and to 

 this the upper part of the scutum is " soldered," while in G. Bar- 

 winii (PI. 1. figs. 13, 21-25) the scutum is free and there is no bar 

 right across the front, though sometimes it has commenced at 

 both sides, thus showing us the early stage of G. Boryi. The 

 'Challenger' specimens do not show the helicine mark on the 

 scutum to which MacGilliyray refers. The differences are so 

 slight that I should have called Darwinii a variety of G. Boryi. 



Gaherea Boryi, however, also occurs in the Southern hemi- 

 sphere, from New South Wales, Adelaide (Victoria), and New 

 Zealand ; but in all these the lateral avicularia are somewhat 

 larger than in the European specimens. 



In G. Boryi there is one vibracular chamber at the bifurcation. 

 There are 18 tentacles. 



In G. Darwinii there are two spities at the lower edge of the 

 oral aperture and two at the distal. 



BuGULA PLUMOSA {Pcillas). (PI. 2. figs. 5-7.) 



See Hincks, Brit. Mar. Polyzoa, p. 84, for synonyms. 



Bugiila plumosa, var. aperta, Hincks, Ann. Sf Mag. Nat. Hist. ser. 5, 

 vol. xvii. p. 261, pi. ix. fig. 6. 



Bugula simplex, Hincks, loc. cit. p. 262, pi. ix. fig. J. 



This seems to be subject to a certain amount of variation in 

 the matter of spines. In some they are scarcely distinguishable^ 

 in others the outer one attains a moderate size. Again, on the 

 inner corner of most specimens no spine can be found, in others 

 only a protuberance, while, again, in some it is distinct. In 

 Trieste I noticed that those collected in the sea had a fairly 

 prominent outer spine, whde those growing in the aquarium had 

 only a protuberance; and there seems to be no difference in the 

 colonial growth of the B. simplex form and the B. plumjsa 

 form from this locality. I have from Trieste typical specimens 

 of both forms, but upon examining a series I am unable to 

 separate them *. 



* In an undoubted B. plumosa from Eoscoff, occasionally a slight prominence 

 on the inner border may be detected. 



