42 BULLETIN OF THE 
arrangement of the individuals in Figure 64. The radial lines repre- 
sent the rows of individuals; the concentric lines separate adjacent 
individuals of the same radial row. The same nomenclature is used 
as in Figure 64, 
In studying Figures 64 and 64°, one of the first facts which attracts 
our attention is that (1) the individuals of the twigs are in pairs, and 
the adjacent individuals of the two rows “ break joints.” In general, one 
finds that the individuals of the same twig are of the same length ; but 
since the two rows of any twig ultimately rest upom one, either the prox- 
imal two individuals of these rows must be of unequal length, or else 
they must arise on different parts of the individual which supports 
them. Both of these cases occur. Sometimes one individual (26 IX.) 
has nearly twice the length of the other (25 IX.), and in other cases 
(9, 10 VL, 11, 12 VI.) the more proximal of the two individuals 
(9, 10 VI.) arises so far proximally on the side of the supporting indi- 
vidual 9-12 V. as to have a total length quite equal to that of the more 
distal (11, 12 VI.). Owing to their different positions upon the indi- 
vidual 9-12 V., these two individuals may be designated as lateral 
(9, 10 VI.) and terminal (11, 22, VI.). The terminal individuals con- 
tinue the ancestral row; the lateral individuals are the first of lateral 
branches. 
This distinction is an actual, and by no means a meaningless one. 
The constant difference in position of the two individuals which rest 
upon one shows conclusively that this branching cannot be regarded as 
dichotomous,.and I may say parenthetically that I shall try to show 
in the general part of this paper that true dichotomy is not com- 
mon in Bryozoan stocks, if indeed it exist at all. Now, since in 
the rows of individuals in which there is no lateral budding the 
distal lies directly terminal to the proximal individual, that individual 
which fulfils this condition at the region of bifurcation of the twig 
must be regarded as continuing the ancestral branch; and that 
individual, conversely, which arises from the side of the single prox- 
imal individual must be regarded as the lateral one. Thus we have 
the stock composed of ancestral and lateral branches as represented 
in Figure 64% 
(2) When two lateral branches are given off from two ancestral ones 
which have had a common origin (and are consequently themselves re- 
spectively ancestral and lateral branches), they are given of’ towards 
each other, This is equally true whether the two lateral branches in 
question arise in the same generation (32 X., 33 X.) or in different 
