od 
VoL. 2] Robertson.—Non-Incrusting Bryozoa. 245 
everted during the expansion of the polypide. Owcia globular, 
membranous, situated at the upper extremity on the ventral side 
of the zocecium just below the operculum (fig. 4, @.). 
As Smitt (’67), Waters (’79), and Jullien (’88) have 
already shown, there has been much misconception in regard to 
the zocecium of Actea. Busk (749) considered the erect, tubular 
portion alone to be the zowcium, and in this error was followed 
by Hineks (’80) who regards the erect tube as the zoccium, 
the horizontal portion as a stolon, which he compares with the 
stolon of the Ctenostomes. Jullien, apparently unaware of the 
observations of Smitt or Waters on this point, criticizes the 
statement of Hincks as to the stolonic nature of the adherent 
portion. This he considers the true zocecium, since into it he 
finds the polypide withdraws. itself on retraction and on its walls 
the retractor muscle fibers are inserted; while the upright 
tubular portion he regards a peristome. Smitt and Waters 
had previously shown, however, that the polypide inhabits the 
creeping portion, and that this is in no sense a stolon. Later, 
Waters (’96) has shown that in the species known as Aetea 
anguina forma recta, the ovary is situated in the creeping part, 
thus affording conclusive proof of the zocecial character of this 
so-ealled ‘‘stolon.’’ 
In the colonies of this species found on the California coast 
(figs. 1, 2), the creeping and erect portions are continuous. 
The polypide when expanded occupies the upright tube, but on 
retraction retreats into the creeping portion almost completely, 
only the tips of the tentacles and the long, delicate sheath with 
its muscles remaining in the tube (fig. 3). In this figure, part 
of the upright tube is represented as broken and the polypide 
is not in a state of complete contraction, but the insertion of 
the retractor muscles on the wall of the creeping part (mus.), 
and the presence of the ovary (ov.) on the adnate ventral wall 
are shown. From the evidence presented it seems to be estab- 
lished that the zocecium of Aetea consists of both the creeping 
and the erect portions and not merely of either one of these. 
In our specimens of Aetea the ocecia are abundant. As 
shown in fig. 4, each consists of a membranous bag situated on 
