138 SIDNEY P. HAKMER. 



of the colony than elsewhere. The branch is developed on the 

 same side as the basal zooecium of an internode, and the last 

 zooecium is usually somewhat produced. In very rare cases, 

 of which the specimen represented in fig. 6 is an example, two 

 branches may be developed from the same internode. 



The articulations which bear the lateral branches are rela- 

 tively short ; even when the branch is developed from z^ or z^ 

 the "basis rami " is never wedged in between two zooecia, as 

 in the last species ; and the joint which bears the branch is 

 nearer to the aperture of the zooecium which has developed 

 it than in C. denticulata. 



The number of zooecia is typically five or seven, the former 

 number being especially characteristic of the members of a 

 helicoid cyme. As in C. denticulata, the definiteness with 

 which the colony grows is frequently indicated by the regular 

 repetition of the same forms of internode in a branch. Thus 

 the greater part of the main axis of the branch whose formula 

 is given on p. 154 is composed of iuternodes of the type {7 + r^) ; 

 in the main axis of the branch given off by the second internode 

 of that stem, (5 + rj alternates regularly with (7 + c^r) until 

 the end of the axis is nearly reached; while in the next line 

 but one will be seen the formula of a branch composed of units 

 of the type (5 + r^) . The regular repetition of iuternodes of the 

 type (5 + rj) in the formation of most of the helicoid cymes is 

 a further illustration of the same thing. In many other cases, 

 however, no such regularity of arrangement was noticed. In 

 a colony found at Plymouth in August, the dominant number 

 of zooecia was seven, although iuternodes with five zooecia were 

 not uncommon. But, in correlation with this increase in the 

 normal number of zooecia, it was found that several iuternodes 

 of nine zooecia occurred, and two of eleven. 



In the terminal iuternodes the number of zooecia may be 

 larger ; in one case observed it was as high as twenty, no 

 growing-point being left. 



The ovicell most commonly replaces the second zooecium of 

 a lateral branch (fig. 6), and is consequently the basal member 

 ol its own (axial) side; iu other cases, however, the ovicell may 



