24 



at right angles, the other rising at an acute angle to the stem. The stem then 

 rises without giving off any more principal branches, but tends slightly towards 



the side on which the l)ranch stands at an acute 

 angle. From the whole surface of the stem and 

 princiijal branches, smaller branches are given oflf 

 which by a kind of repeated dichotomy give rise 

 to the jjolyp-bearing twigs. The lower flattened, 

 leaf-like branches almost surround the stem, 

 leaving only two small free spaces which are 

 occupied by two smaller branches which arise at 

 a lower level. Of these smaller branches the 

 stalk is cylindrical in the one, flattened in the 

 other, and in both the upper portion is flattened 

 and occupies the triangular sjjace left between 

 the edges of the flattened folia. Directly above 

 these openings there arise two flattened branches, 

 the upper portion of which divides more or less 

 similarly to the ordinary branches, and at the base of the principal branches 

 one or two slightly flattened branches also occur. From the edges of the 

 flattened folia small ordinary branches arise. 



Fior. 11. D. colombiensis. 



Fig. 12. D. colombiensis. — b, from stalk cortex ; c, from stalk canal walls. 



The polyps are arranged in small groups of four to eight which stand closely 

 together on the upper part of the polyparium and more distantly in the lower 

 part. On the edges of the flattened branches the polyps occur singly or in 

 small groups. They measure about O'O mm. in height and 0'6 mm. in breadth 

 and are placed at a right or obtuse angle on the stalk, which measures 1 mm. in 



