species are distinct from one another it is probable that they have often been confused by 

 other writers. 



D'Orbignv's specimens were obtained in the Falkland Islands, and his description and 

 figures represent a form which is much coarser in its habit than the 'Siboga' specimens, the 

 series consisting of 3 — 4 zooecia. The basal surface of the branches appears to be very convex ; 

 and there is no indication of cross-connexions or of rooting columns l ). A specimen obtained 

 by Mr Darwin, during the 'Beagle' Voyage, at the Albrolhos Islands, Brazil, and now in the 

 Collection of the University Museum of Zoology at Cambridge, agrees well with D'Orbignv's 

 account. The branches are robust, the zooecia being usually 4 in each of the alternating series. 

 When an ovicell is formed the branch widens greatly, and the number of zooecia in one series 

 rises to 6 or 7 ; represented, as in the 'Siboga' specimens, by peristomes isolated from one 

 another by the roof of the ovicell. A similar enlargement of the branch may occur at a 

 bifurcation, without the formation of an ovicell. The only ooeciostome which is satisfactorily 

 seen is much compressed, with a narrow ooeciopore, much elongated in one direction, looking 

 directly frontally and placed obliquely. The much coarser habit, with the absence of connexions 

 between the branches, together with the characters of the zooecial series and of the ovicell, 

 appear to me to point to the fact that the 'Siboga' specimens do not belong to D'Orbignv's 

 species. The basal surface of Mr Darwin's specimen is very broad, nearly flat in the middle, 

 and shows distinct longitudinal septal lines and a certain number of transverse lines of growth. 



T. interjuncta was described, but not figured, by MacGillivray from Victorian specimens. 

 In the existence of connexions between the branches and of rooting columns from their basal 

 surfaces, it obviously comes very near the Malay specimens. But although MacGilliyrav 

 describes it as resembling a slender form of T. milneana, the evidence of Victorian specimens 

 in the Cambridge Collection shows that it is a more robust form than those from the 'Siboga' 

 clredgings. The Victorian material alluded to includes only a single ovicell; which possesses a 

 marked rounded swelling in the middle line. On the proximal side, this swelling opens by an 

 ooeciostome which is hardly represented by more than a greatly compressed, slit-like ooeciopore, 

 opening almost directly from the swelling in a vertical plane, and facing proximally. The long 

 axis of the ooeciopore is transverse, and is convex proximally, the slit being vertical and 

 accordingly only visible when the ooeciostome is looked at from the proximal end of the branch. 

 The zooecia are usually 3 — 4 in a series, and are distinctly larger than those of the 'Siboga' 

 specimens. I do not feel convinced that these are identical with MacGillivray's species. 



Waters 2 ) has compared T. milneana and T. interjuncta from Port Jackson; but I do 

 not feel sure that his determination of T. interjuncta is correct. The characters of the ooeciostome 

 in Waters' specimens appear to show that these belong to the same species as the 'Siboga' 

 material; and that they are hence not identical with MacGillivray's species. The ovicell of a 

 Mediterranean specimen (Capri) which has been described as I. milneana and figured by Waters 8 ) 



1) These structures may, however, occur in this species (Waters, A. W., 1905, Tin'. Cape Hovn", J. Linn. Soc, Zool., 

 XXIX, p. 249). 



2) Waters, A. W., 1SS7, "Bry. N. S. Wales", Pts II, III, Ann. Mag. Nat. Hist. (5) XX. PI. VI, fig. 29: pp. 256, 257. 



3) Ibid., 1S89, '•Ovicells Cycl.", J. Linn. Soc, XX, p. 279, Tl. XIV, Hg. 8. 



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