20 BULLETIN OF THE 
as occurring on Gonopodaria and P. Belgica, budding does occur to a 
slight extent on Arthropodaria, and still more profusely on Urnatella. 
There is one genus, however, Barentsia (Vigilius, 7844, p. 86), which buds 
sparsely and has an unsegmented stalk. Here, however, as in Urnatella 
(Plate VI. Fig. 58) and Arthropodaria (?), there is a septum between the 
branches and the main stalk. 
Finally, in all Pedicellinidee which have been studied carefully there 
is a septum between the stalk and calyx. 
One may bring these scattered facts of distribution of the septum into 
some sort of unity by saying that in the Pedicellinidee every calyx and 
every lateral branch (where such exists) is partly cut off from communi- 
cation with the interior of the mother stalk by septa. This is effected 
by the production of these organs at the place of junction of the calyx 
and the lateral buds to the stalk, and in some cases also by the partial 
division of the stalk itself into compartments by septa. The transverse 
septa must have either a morphological or a physiological significance. 
They might be regarded as a part of the wall of zocecia, equivalent to 
the zocecia of Paludicella, and therefore to be morphologically equiva- 
lent to the septa of Paludicella. On this hypothesis each segment of 
the stalk of Urnatella would be an (incomplete) individual. The idea of 
the individuality of the segments would seem to be sustained by the fact 
that each gives rise to similar buds, and that apparently any segment 
has the capacity of regenerating the lost calyx, or end of the primary 
stalk. On the other hand, dissepiments might be regarded as structures 
which had grown across the originally unsegmented stem to fulfil some 
need of the organism. Comparative anatomical studies seem to me to 
favor the second view. In Loxosoma, and in most marine Pedicellinide, 
we find a stalk without dissepiments. In other forms dissepiments 
are few and variable in number, in still others they are constant in 
occurrence, and from the segments arise buds. Finally, in Urnatella, 
the segments are separated by the dissepiments, each becomes more in- 
dividualized, and has the capacity of giving rise to buds having the same 
arrangement. The differentiation of the separate segments has gone so 
far that one can hardly see in the stalk of Urnatella, resembling a string 
of beads, the assumed smooth cylindrical stem of its Pedicellina-like 
ancestors. 
If we seek for an explanation of the dissepiments, I think it is to be 
found in the protection of the stock against the influx of water and de- 
stroying organisms at the time of the loss of calyx or lateral branches, 
which would make regeneration impossible. This is the same hypothe- 
