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5 mm. in that measurement. In all essential respects, including the characteristic ovicells, these 

 specimens agree completely with those belonging to the 'Siboga' Collection. 



The profuse development of cancelli is another very distinctive feature, especially as this 

 character is not ordinarily found in species of "fdmonea". They are present in all parts of the 

 zoarium except on the peristomes of the zooecia and on the porous lateral windows of the 

 ovicells. Both on the basal and on the fronto-lateral surfaces they originate by the subdivision 

 of the interzooecial grooves. Examination of the arowinsr ends of the branches shows that a 

 cancellus commonly includes several pores. 



The feature which is, however, specially distinctive of the present species is the occurrence 

 of thin lateral regions in the wall of the ovicell, which have been alluded to above as the lateral 

 porous windows 1 ). The pores are here much more numerous than in any other part of the 

 colony ; and they are indeed arranged so closely that there is very little interval between any 

 tvvo pores. In the 'Siboga' material the ovicell commonly corresponds in length with four of 

 the oblique series of zooecia on each side (fig. 7). In these cases it follows that there will be 

 three porous windows (w) on each side of the ovicell; but in ovicells which correspond "with a 

 smaller number of zooecial series, the number of windows is smaller in proportion. If an ovicell 

 extends into the bifurcation of a branch, a distal window is generally present, in addition to 

 the lateral ones. The windows, which are longest in the fronto-basal direction, are usually quite 

 distinct from one another, as shown in figs 6 and 7 ; and the series of zooecia then extend 

 along the sides of the ovicell without any obvious modification. In a few cases I have found 

 that the lateral windows may be confluent along their basal portions ; and the zooecial series 

 are then interrupted ; a median zooecium occurring in its usual place, the middle zooecium of 

 the series being suppressed, and the outermost zooecium being found on the basal side of the 

 confluent part of the windows, separated by a considerable interval from the median zooecium 

 of the same series. 



The lateral windows of the ovicells of this species have already been described by 

 Waters (1887; see synonymy); and the ooeciostomes have been described by the same author 

 in a recent paper (19 14). One ooeciostome is present in each ovicell, corresponding with one 

 of the lateral windows, either on the inner or on the outer side (as determined by the relation 

 of the ovicell to the preceding bifurcation of the branch). Where three lateral windows are 

 present on one side I have generally found the ooeciostome on the distal window ; less commonly 

 on the middle window ; and very rarely 011 the proximal window. The thin perforated plate is 

 surrounded by a slightly raised margin, and part of the more frontal portion of this margin 

 is produced into a convex hood (fig. 7, o), which constitutes the ooeciostome. In the majority of 

 cases this structure is developed from the proximal side of the window, and is directed distally, 

 as in fig. 7 ; but in a smaller proportion of cases it is developed from the distal side of its 

 window and looks proximally. The back of the hood of the ooeciostome rests against the 

 adjacent zooecium, usually the middle one of the series. The ooeciopore is completely concealed 

 in a frontal view of the branch; but it can be found by arranging the ovicell so as to be able 



1) These stvuctures are stated by Waters (1914, p. 845) to be absent in specimens from Zanzibar. 



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