BUGULA 429 



In both the typical form and the variety the outer distal corner of the zooecium is 

 inrolled so that the proximal spine is directed more or less frontally. The Siboga 

 material (Harmer, 1926, p. 447) has little or no inrolling of the corner, and the spines 

 are both directed distally. 



All these colonies of var. cuspidata have stout, usually annulate, rootlets, springing 

 from the basal surface of the zooecia and passing, independently of each other and of 

 the zooecia, to the substratum. In one of the Terra Nova colonies the branches spread 

 fanwise above the surface of a Cellepora and drop these rootlets at such frequent intervals 

 that they form a forest of rootlets. These rootlets are thickest at the end farthest 

 from the colony. This colony has a very long, slender, turbinate ancestrula (Fig. 38 C). 

 From the shape of its opesia it appears that it had spines all round it. It is very similar 

 to that of typical Bugula cucullata figured by Harmer (1926, pi. xxx, fig. 7). The rootlets 

 on the first two zooecia show little trace of the annulation which is such a marked 

 feature of those, often longer, ones, that were formed subsequently. The main part of 

 the colony is opaque, spineless and without avicularia. Here and there ancestrula-like 

 zooecia have been budded from these presumably old zooecia and have given rise to 

 fan-shaped, glistening shoots, with spines and avicularia. A similar budding process 

 was seen in B. calathus and B. dentata. 



3. Bugula dentata (Lamouroux). 



Acamarchis dentata Lamouroux, 1816, p. 135, pi. iii, figs. 3 a, B. 



Bugula dentata Harmer, 1926, p. 439, pis. xxx, figs. 5, 6, xxxii, figs. 21-25 (references); Living- 

 stone, 1929, p. 53; Hasenbank, 1932, p. 329; Okada, 1934, p. 5, pi. i, fig. 9. 



Station distribution. Cape Verde Islands: St. 299. 



Geographical distribution. Madeira (Norman); Cape Verde Islands (Waters; Discovery); 

 John Adams Bank, off Brazil (99.7. 1 .4618); South Africa (Krauss; Busk; Hasenbank; O'Donoghue; 

 Harmer); Red Sea (27.5.23.1); Indian Ocean (Thornely); Amsterdam Island, Indian Ocean 

 (Hasenbank); Malay Archipelago (Calvet; Marcus; Harmer); Australia (Lamouroux; Busk; 

 MacGillivray ; Waters ; Kirkpatrick ; Harmer) ; Tasmania (Busk) ; New Zealand (Busk ; Livingstone) ; 

 Japan (Ortmann; Yanagi and Okada; Marcus; Okada); Loyalty Islands (Philipps). 



In the zooecia of this specimen the opesia is shorter than that described by Harmer, 

 and the avicularium, which is as usual on the outer side of the zooecium, is attached at 

 a point proximal to, or sometimes level with, the proximal end of the opesia. Such a 

 condition is seen in parts, particularly the proximal part, of quite typical colonies (e.g. 

 the specimen from Siboga St. 50, 28.3.6.280), and it is possible that the small colony 

 obtained by the ' Discovery ' would have produced zooecia with the longer opesia if it 

 had developed further. Ovicells and enlarged trifoliate avicularia are absent from this 

 specimen, and the spines are slender and without any distinct basal joint. The main 

 colony is about 10 mm. long and complete basally, with ancestrula and basal tuft of 

 rootlets. The older zooecia contain brown bodies and from this part of the colony spring 

 eight adventitious branches each of which starts with an ancestrula-like individual and 

 shows the usual gradual transition to zooecia of typical form. Each adventitious branch 

 springs, apparently as a bud, from the distal part of the outer lateral wall of a zooecium, 



D XXII 17 



