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proximal (inner) half of such a main branch a secondary branch is given off, 

 and excepting the extreme, or more rarely the two extreme secondary branches 

 on each side, which bear a row (4 — 5) of cylindrical internodes like those of the 

 terminal parts of the main branches, all the other secondary branches consist 

 in the complete state of a row of zocecia, of which each again ends in a row 

 (3 — 4) of the cylindrical internodes. In such a small colony we may thus distin- 

 guish between four different forms of internodes, namely (1) stem-internodes, (2) 

 bifurcate internodes of the main branches, (3) the zooecia, and (4) the narrow 

 cylindrical internodes. While the colony, when placed on a level, has the form 

 of a stalked fan, the rays of which decrease in length from within outwards, it 

 has in its natural position almost the shape of a ball with a pear-shaped incis- 

 ion on one side bounded by the two main branches (fig. 6 a). 



The zooecia (6 d, 6 c, 6 f), the two lateral surfaces of which meet in a poin- 

 ted basal edge (6 s), have, when looked at sideways, an almost semi-circular out- 

 line, though the proximal half of the dorsal surface is a little incurved. The 

 semi-elliptical aperture, situated in the distal part of the zooecium, has an almost 

 straight proximal margin and is covered by a slightly chitinized, simple oper- 

 culum, the proximal margin of which is more chitinized, and the opercular arch 

 of which is situated in the margin itself. Proximally to the aperture we find a 

 rather deep cryptocyst depression, occupying almost half the length of the zooe- 

 cium and only separated from the aperture and the lateral surfaces by a narrow 

 marginal portion. The proximal part of the zooecium is arched, sometimes almost 

 stalk-like narrowed and furnished with a very thick frontal wall (fig. 6 d). The 

 cryptocyst is also very thick-walled, particularly the distal part, which projects 

 into the zooecium with a very rounded thickening (fig. 6 d), and in the frontal 

 wall of this portion, proximally to the aparture, a small transversely oval hollow 

 is seen. Further back, in the approximate centre of the length of the zocEcium 

 and immediately on the proximal side of the above mentioned, very arched por- 

 tion, is a somewhat larger, transversely oval area, which is removed a little from 

 the central line, and which has a transverse slit in the whole of its breadth. In 

 each zooecium the inner cavity shows four distinctly separate segments, which 

 we may indicate by the letters a, /S, y, d (6 c), and the obliquely ascending distal 

 wall, furnished basally with one single-pored rosette-plate, is situated between 

 the segments fi & y 



The stem-internodes (figs. 6 t, 6 u, 6 v, 6 x), of which the lowest (6 i) has a 

 long, narrow, chitinized proximal part, are long, spindle-shaped-cylindrical and 

 when fully developed, very thick-walled. The inner lumen is as in the zooecia 

 divided into four segments of different width and shape, «, /S, y, 8, corresponding 



