172 SIDNEY F. HARMER. 



After the branches have been given off, the ovicell becomes 

 perfectly free, and is in this part considerably inflated. The 

 tubular aperture arises near the back of the ovicell, and is 

 usually bent somewhat backwards from its point of origin ; so 

 that, in looking at the branch from its "front" surface, the 

 base of the tubular aperture is nearer to the observer than its 

 distal end. 



In C. geniculata, on the contrary, a common arrangement 

 is as follows: — The basal member of the internode is an ordinary 

 zocecium (tigs. 7 and 8), which gives rise to the ovicell as the 

 second member of the internode. Immediately above the 

 ovicell is another zooecium, which gives off a lateral branch 

 near the level of the upper end of the ovicell. The basal 

 zooecium itself gives off a branch on the opposite side to the 

 ovicell. The internode may thus be represented as — 



{l + Ov. + l} 



I I 



jT" rj (counting the ovicell as the basal member of its own side). 



The ovicell itself is distinctly smaller than in C. cornuta, and 

 is not much inflated at its upper end. Its tubular aperture is 

 most distinctly bent forwards from its base, sometimes at a 

 very sharp angle, and the actual aperture is smaller than in C. 

 cornuta. Moreover, the ovicell is not free, as in the latter 

 species ; the upper zooecium of the internode being closely 

 attached to its back along the greater part of its course. This 

 zocecium ultimately becomes free from the ovicell, and curves 

 forwards above the upper end of the latter. 



In other cases the ovicell may be the third member of the 

 internode, each of the two zooecia below it giving off a branch ; 

 and two zooecia, each bearing a branch, may occur above the 

 ovicell. The commonest arrangement seems to be either that 

 given in the above formula, or the occurrence of three branch- 

 bearing zooecia, one of which is below the ovicell and the other 

 two above it (cf. Busk's fig. 2). The ovicell is, iu any case, not 

 the lowest member of the internode, aud one or two zooecia 

 arc always attached to its back. 



C. geniculata is a slenderer and more delicate form than 



