Embryogeny of the Bryozoa. 399 
fills the whole cavity of the peduncle, and which, I think, we 
may regard as the homologue of the funiculus of other Bryozoa. 
It seems probable that all the oral surface must, in the ances- 
tral type, be regarded as divided into three parts:—l1, the 
upper part, destined to form the tentacular chamber, and into 
which would open in the types in question, below, the diges- 
tive tube and above, the invagination of the aboral surface 
destined to form the aperture of the cell; 2, the pedal gland, 
formed by the circlet; and 3, the intermediate portion, the 
margin of the vestibule, reduced to a cord uniting the gland 
with the polypide, entirely composed of connective cells, and 
representing the funiculus in the Ectoprocta, and in the Ento- 
procta the connective reticulum of the peduncle. 
If from these data we attempt to construct a general type 
of adult Bryozoon, we shall see that there are grounds for 
distinguishing three surfaces :—1, the foot, corresponding to 
the oral pole; 2, the frontal surface, corresponding to the 
surface which answers to the mouth (figs. 6, 7, 8, Hr); and 
3, the tergal surface, corresponding to the anus (figs. 6-8, 
Tq), the two latter surfaces both forming parts of the aboral 
surface which forms the entire integument. 
In the Entoprocta these three distinct surfaces are easily 
recognized ; and fig. 6, in which I have further carefully indi- 
cated the separation of the calice and peduncle, will show 
plainly at the first glance the distinctness of these three great 
divisions. 
In the Ectoprocta the original arrangement seems to me to 
be that in which the cell comes to be developed in the direc- 
tion of its height, as in the Sertalarie, Bugule, &e.; in 
these forms (fig. 8) we also very clearly distinguish the three 
surfaces, pedal (Pd), frontal (Hr), and tergal (Tg). Lastly, 
in the forms which are spread out into a plate, such as the 
Hscharina and the majority of the Chilostomata, we can 
strictly establish the same distinction as I have shown in 
fig. 7. It isindeed to be noted that, in this last type, it is the 
tergal face whose growth almost always gives origin to the 
first bud*. 
* In a multitude of groups the terms ventral and dorsal have been 
the source of endless confusion and ambiguity—among the Bryozoa, to 
take only a single example. The authors who give the name of the ven- 
tral surface to the surface applied against the ground for reptation, will 
regard the fixed surface (Pd) as ventral and the free surface as dorsal; 
on the contrary, those who regard as ventral the surface upon which the 
mouth opens will regard the free surface as ventral and the fixed surface 
as dorsal. The two kinds of interpretation have already been made use 
of without either of them satisfying the mind; for both characters 
(application against the ground and the existence of a mouth) are justly 
