BUGULA TURBINATA. 79 



of intert-vvining tubular fibres by "wbich it is attached. 

 When living it is of a rich orange-colour, but fades to a 

 pale straw-colour, or to a pearly Avhite, when dried. 



Amongst the other points which distinguish B. turbi- 

 nata from the last species, are the following : the cells are 

 arranged upon the branches in a greater number of longitu- 

 dinal rows ; in B. avicularia there are almost universally 

 two ; in the present form the segments commence with 

 two near the base, but the number rises in the upper por- 

 tions to three, four, five, and occasionally six. B. turbi- 

 nata has only a single spine on the outer and inner angles 

 of the aperture. Its ovicell is smaller, and is readily dis- 

 tinguished by its hyaline border and the curious process 

 (sometimes slightly pointed, but more usually rounded, at 

 the top) which rises from it and occupies the centre of the 

 front surface. 



But the most important distinctive character is supplied 

 by the avicularium, which, with its well rounded head, 

 and short, sharply bent beak, contrasts strongly with the 

 somewhat slender, compressed, long-billed appendage of B. 

 avicularia. The avicularium is present on every cell ; but 

 those on the outer edge of the branch, which have more 

 space to work in, are very much larger than the rest. 

 The number on a specimen of average size is very consi- 

 derable ; and when they are all in active and energetic play, 

 and the polypides are darting in and out, the surface of 

 the zoarium presents a singularly animated scene. 



As in the preceding species, the o^dcells are developed 

 in amazing numbers, and the branches commonly appear 

 as if studded over with innumerable tiny pearls. 



B. turhinata seems to be abundant and widely distri- 

 buted, but has not yet been noticed in the further north. 



