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II. The Divaricatae are characterized by : 
(a) the profuse branching of the polyparium; 
ip) the length and slenderness of the twigs; 
(c) the divergent separateness of the polyp bundles; 
(d) the absence of anything than can be called bunches of the Glomerate type or umbels of 
the Umbellate type. 
* 
It should be noted, however, that a Divaricate polyparium often has a continuous contour 
like that of a well-pruned tree (Plate XVII, Fig. 2). 
III. The Umbellatae are characterized by : 
(a) the umbel-like or sometimes corymb-like aggregates formed by the terminal twigs, the heads 
of the umbels being bundles of polyps; 
(1 b ) the disposition of all or most of the polyp heads on the surface of the colony (Plate 
XVII, Fig. 3). 
Thus the Umbellatae differ from the Glomeratae, and agree with the Divaricatae in 
showing much minor branching. They differ from the Divaricatae in the presence of umbels or 
corymbs of polyp bundles and in the entirely superficial arrangement of the polyp heads. As 
this continuous superficial disposition is obviously advantageous — giving all the polyps equal 
exposure for nutritive and respiratory purposes — we may regard the Umbellatae as the latest 
expression of evolution of the Dendronephthya polyparium. 
Of minor importance is the question whether or not the umbels combine into large 
secondary bunches rising like hillocks on the surface, or the question of the shape of the 
polyparium whether flattened or quite symmetrical, whether spherical or disc-like, and so on, for 
these features probably depend to a large extent on local environmental conditions. 
While there appears to be a deep constitutional contrast between Glomerates, Divaricates 
and Umbellates, we cannot but regard it as fallacious to propose a major splitting within these 
three sections on growth characters such as the uniformity or irregularity of the surface outline. 
Similarly it seems to us that there is a strong risk of fallacy in Kukenthal’s Spinulosa-<gx oup 
where the polyparium has no continuous contour. 
Specific Characters. 
Before considering the specific characters selected for examination and criticism, let us 
recall the external spiculation of a Dendronephthya polyp (Textfig. 1). 
The ascending order is as follows: 
(1) The supporting bundle (Stlitzbiindel). This may consist of (a) several spicules more or less 
of the same size (the ensheathing type), or (b) one or more may be distinctly longer than 
the others (the buttress type). These spicules may attain a length of 3 or even 4 mm. and 
may project beyond the anthocodia for a distance of 0.5—-1.5 mm. In addition to the 
spicules of the supporting bundle proper, there may be a few accessories which often mingle 
with those of the polyp stalk. 
