16 BULLETIN OF THE 
22, 29, gn.) lies between vas deferens and nephridium, is elongated trans- 
versely, and slightly constricted in the median plane. One can distin- 
guish a central'region composed of fine fibres running transversely, and 
a cortical region of cuboidal, deeply staining cells with large clear nuclei. 
I have not succeeded in tracing any peripheral fibres from this gan- 
glionic mass, as Ehlers has done in another Endoproct. 
III. | NoN-SEXUAL REPRODUCTION. 
1. Architecture of the Stock. 
Urnatella forms stocks by budding. As in other Bryozoa, the buds 
are normally produced in a very regular manner. TI believe that I have 
determined the law in part, although it has exceptions, as the law 
of budding in every Bryozoan stock has. As Leidy has stated, several 
vertical stalks may arise from the same horizontal plate. A single stalk 
may remain unbranched, giving rise to new individuals at its distal end 
only, or it may give rise to branches which come off irregularly from a 
few segments. Usually only one branch arises from a single segment, 
but occasionally two do so (Plate V. Figs. 35, 38). 
The length of these branches and the number of their segments decrease 
towards the distal end of the main stalk, and the conclusion seems jus- 
tified that it is only at the distal end that they are formed. Excepting 
for these occasional branches, the lower segments of the stalk are bare of 
any branches or polypides. The distal end, however, is usually crowded 
with polypides so thickly as to make it difficult to count them or to de- 
termine their points of attachment (cf. Plate V. Fig. 30). 
A very casual observation, however, shows that the buds from the 
main stalk are of two kinds; first, those which have given rise to a 
linear series of segments at the distal end of which is a calyx, and these 
are what I have called branches; and, secondly, those consisting of a 
stolon-like process, from one surface of which arise calyces resting upon 
a stalk of usually one segment only. The surface of the stolon upon 
which such polypides are placed is a definite one, namely, that which is 
turned towards the distal end of the main stalk. The budded branches 
and also the stolons are grouped upon the oral side of the adult stalk. 
In the clearest cases, in young or not too richly branched stocks, I 
find the branch arising on the oral surface of the segment, and between 
two stolons, which are therefore more nearly lateral (Plate V. Figs. 37, 
38, 40, 42). 
