I 4 2 



to look into the mouth of the ooeciostome, when it is found to be a narrow slit, elongated 

 transvèrsely. The ooeciostome is thus very similar to that of Tubulipora phalangea, as described 

 by me in an earlier paper l ). 



During the development of the ovicell the lateral windows are the parts which calcify 

 last. The cancellate frontal wall is thus completely formed while the windows are closed merely 

 by ah uncalcified membrane. I have not obtained specimens in which the complete development 

 of the normal ovicell can be traced ; but in a specimen from Torres Straits, in which an abortive 

 attempt to produce an ovicell has been made, two of the median zooecia on one side and three 

 on the other have each developed a spoon-shaped process which passes towards the middle 

 line of the branch, at a level considerably raised above that of the general surface of the 

 branch. The processes have not met one another; but this case may give some indication of the 

 way in which the roof of the ovicell is normally formed. In this instance one of the branches 

 immediately beyond the next bifurcation has developed a normal ovicell; but in other cases the 

 production of an ovicell seems to exhaust the energy of growth, in this respect; no second 

 ovicell being formed on any branch. 



I find comparatively little variation in the present species, but there is some variation 

 in the form of the orifices. The typical number of zooecia in a series is three ; but two are 

 not infrequent and four are occasionally observed. The orifices are usually oval, corresponding 

 with some compression in the peristomes; the longer axis of the oval being in the direction of 

 the row of orifices of the series. The median peristome is usually long; and those of opposite 

 sides diverge from one another. The orifice of this zooecium is frequently pointed on its median 

 side, so that it is not a true oval; and the peristome is often produced into a distinct point 

 on the same side, in such a way as to resemble a quill-pen. lts outer margin is less often 

 produced into a point. The next peristome is distinctly shorter than the median one, and in 

 some cases is produced into a marked point on its outer side, the orifice being then pointed 

 on that side. The outermost orifice is usually level with the surface of the branch, and no 

 peristome is present. The middle line of the frontal surface of the branch is generally occupied 

 by a pronounced thickening band of calcareous matter, from which the median peristomes 

 diverge. The outer margin of the basal surface of the branch may be slightly serrate, 

 particularly in young branches. 



Me as ure men ts , in a: — 



Width of branch, lower part of fig. 8, 500 ; 



Width of branch, upper part of fig. 8, 350 ; 



Length of ovicell, fig. 6, 1,300; 



Longest diameter of proximal lateral window of ovicell, fig. 6, 250 ; 



Longest diameter of ooeciostome, fig. 7, 100 ; 



Longest diameter of orifices of zooecia, up to 100. 



1) Harmer, S. F., 1898, "Dev. Tubulipora", Quart. J. Mier. Sci., XLI, p. 94, PI. VIII, figs. 5, 6. 



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