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diameters of a zooecium. They thus appear to be arranged in a single row along the branch, 

 and the alternate disposition is not obvious. The ends of the branches are rounded or truncate. 



V. spinosa, the type-species, is distinguished by having " spinous" ends to the branches, 

 composed of small barren internodes which are acutely pointed. The zooecia are not obviously 

 paired, but occur in what looks like a single row, three being commonly developed by each 

 internode, at considerable distances apart. In this respect, and in the apparently uniserial 

 arrangement, it agrees with the Japanese specimen. 



In two points — the character of the branching and the existence of a gizzard — the 

 account given above differs from Busk's description. But I have convinced myself, by a comparison 

 with the original material, that the 'Siboga' specimens, which are from a locality very near 

 that from which V. papuensis was first described, really belong to Busk's species-, and indeed 

 that they agree extremely closely with his specimens. The type-material, in the British Museum, 

 consists of a specimen, Sy. 12. 9. 938, in spirit; and a slide, 87. 12. 9. 937, which was no doubt 

 prepared from the spirit-specimen. In describing V. trichotoma, which immediately succeeds 

 V. papuensis in the 'Challenger' Report (p. 37), Busk emphasises the trichotomous division of 

 the primary branches as a peculiarity distinctive of the former species; and therefore as a 

 difference between it and V. papuensis, in which the zoarium is said to branch dichotomously 

 in one plane. It may be inferred with some confidence that Busk wrongly assumed the mode 

 of branching visible in the mounted slide of V. papuensis (which shows only a lateral branch 

 of the colony) to be the only mode occurring in the colony. But a reference to the spirit- 

 specimen shows that in the main stem the branching of V. papuensis is as trichotomous as in 

 the 'Siboga' specimen. The stem is in fact angulated at the nodes, from each of which a pair 

 of divergent branches, not in one plane, are given off. In some of the nodes the stem might 

 appear to dichotomise, if examined superficially ; but on closer inspection it is seen that in these 

 cases one of the two "branches" has a thick cuticle and in other respects shows itself to be the 

 prolongation of the stem. The other branch has the thinner cuticle and the simple dichotomous 

 mode of dividing which characterise the lateral branches in general. 



With regard to the second point, the mounted slide, on which Busk probably relied, 

 does not show the gizzard convincingly. But the zooecia of the spirit-specimen are suffkiently 

 transparent to allow the gizzard to be seen quite distinctly. It is thus seen that V. papuensis 

 conforms to the generic diagnosis given by most authors, in possessing a gizzard. 



V. trichotoma is represented in the British Museum Collection by three slides (87. 12. 9. 

 939; 99- 7- ï-43 ?; 99- 7- 1 • 43 10) which have unfortunately suffered greatly by the drying up 

 of the medium in which the specimens were mounted. The trichotomous branching described 

 by Busk is well seen, however, in those parts of the colony in which the stem is covered by 

 a thick chitinous ectocyst. The terminal branches are "furcate", as Busk stated; and there is 

 indeed no obvious difference between these forms and V. papuensis. The greater diameter of 

 the sterns mentioned by Busk as a distinctive feature of V. trichotoma seems to me also without 

 rauch significance; since, as in the type of V. papuensis, the diameter becomes less in passing 

 from the proximal to the distal parts of the colony. The balance of evidence appears to me in 

 favour of regarding V. trichotoma as a synonym of V. papuensis. 



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