6 Tun. 
VI. TUNICATA. 
from his observations on Goodsiria dura and Perophora annectens. In 
Goodsiria he finds the budding to bo pallial, and that the buds become 
separated at a very early stage from the young zooids which produce 
them. He finds no evidence for believing that buds can be formed in 
the vessels of the common test by the aggregation of undifferentiated 
cells from the blood. The inner (future endodermal) vesicle of the bud 
is formed from the wall of the peribranchial cavity of the parent (P of 
epiblastic origin). The pericardium and heart arise from the postero- 
ventral wall of the inner vesicle. The hypophysis and ganglion arise 
as a “dorsal tube” which is nipped off at a very early period from the 
dorsal wall of the inner vesicle. The ganglion is a thickening on the 
ventral surface of the tube, or a cell mass that forms the connection 
between the tube and the vesicle, and so is of “ endodermal ” origin. 
In Perophora the buds are, of course, derived from the stolon, and 
one of the most remarkable points established by Ritter is that the 
developing blastozooid is connected with the partition of the stolon, not 
by its branchial sac, but by the left peribranchial sac. Ritter has 
specially directed his attention to the points left in doubt by Kowalevsky. 
He considers that the more recent writings of Yan Beneden, Julin, and 
Pizon have obscured rather than cleared up these points. He comes to 
the conclusion, not without some hesitation, that the origin of the peri- 
cardium and heart is from the inner vesicle. He also shows conclusively 
that the relations of the pericardium in Perophora differ very greatly 
from those described in Clavelina by Van Beneden and Julin. There is 
no epicardium in Perophora , and the pericardium does not at any time 
communicate with the partition of the stolon. Ritter considers that the 
process of budding has probably arisen independently in these two genera 
— Perophora and Goodsiria. 
Pizon has studied the formation and fate of the follicle cells in 
Molgula socialis. He finds there are also cells expelled from the ovum 
which form a layer inside the follicle. Floderus has also studied the 
same subject, from the ovarian egg onwards, in many species of Simple 
Ascidians. He gives a detailed account of the formation of the layers 
of the follicle. 
c. Geographical Distribution. 
Willey gives some notes on the Ascidians present at Raluin, New 
Briiain, and describes a new species, Styeloides eniscerans. 
Kristine Bonnevie describes eleven species of Simple Ascidians, and 
ten species of Compound Ascidians from the Norwegian North Atlantic 
Expedition. Five of the Simple Ascidians are new species. They were 
found on the Norwegian coast, in the North Atlantic, and in the Arctic 
Ocean. 
Lon mann gives three new species of Appendicularians which were 
collected by Yanhoffen on his expedition to Greenland. He also describes 
the formation of the “ house ” as a cuticular formation. 
Borgert discusses the distribution of the Doliolkhe collected on the 
* Yettor Pisani ’ Expedition. Doliolum tritonis and D. nationalis are 
now recorded from the Pacific. 
Roule describes the Simple and Caullery the Compound Ascidians 
collected during the * Caudan ’ expedition in the Bay of Biscay. One 
new species, allied to Ascidia mentula , was found. 
Kialr gives an account of the distribution round the Scandinavian 
coasts of forty species of Simple Ascidians. 
Lou mann gives a very full discussion of the distribution, both bathy- 
metrical and horizontal, of the numerous species of A ppendiculariidce 
collected during the Plankton Expedition. It is illustrated by tables, 
coloured maps, and charts. 
