OBELIA GELATINOSA. 151 



stolon, as well as ill the axils, and are in some cases 

 borne on rather long peduncles. The number of gono- 

 zooids liberated from a colony of this kind, in which the 

 capsules, each containing perhaps a dozen of them, cover 

 a large proportion of the shoots, and are crowded in clus- 

 ters on the creeping fibre, must be enormous ; and it must 

 be remembered, in estimating the produce, that each of 

 the zooids bears the seed of many colonies. Specimens 

 are often coloured red, the colour being due to a very 

 minute alga, which covers the surface with a network of 

 chain-like vegetation. O. geniculata is a phosphorescent 

 species ; and the sudden illumination of a forest of it on 

 some sombre Laniinariaii frond is a truly beautiful spec- 

 tacle. If it is agitated in the dark, a bluish light runs 

 along each stem, flashing fitfully from point to point as 

 each polypite lights up its little lamp. 



Hab. On seaweed, and especially the fronds of Lami- 

 naria digit ata, near low-water mark; very common and 

 generally distributed. 



[Massachusetts, U. S. (Agassiz) : Hamilton Inlet, La- 

 brador, in 15 fath. (T. H.): North Cape and neighbouring 

 coasts (Sars).] 



2. O. GELATINOSA, Pallas. 



SEIITULARIA GELATINOSA, Pallas, Elench. 116; Fleming, Edinb. Phil. Journ. 



ii. 84. 

 LAOMEDEA GELATIXOSA, Lamx. Corall. flex. 92 ; var. (3, Johnst. B. Z. 104, 



pi. xxvii. fig. 1 ; Hincks, Devon. Cat., Ann. N. H. (3rd eer.) 



viii. 259. 

 CAMPA.VULARIA GELATINOSA, Lamk. An. e. V. (2nd ed.) 134. 



Plate XXYI. fig. 1. 



SHOOTS clustered, rising from a fibrous and spongy 

 mass ; STEM compound, made up of numerous delicate 

 tubes, closely bound together, tapering upwards, straight 



