216 RITTER. (VoL. ATT: 
different in the two cases, it seems rather probable, at least 
not at all improbable, that there may be important differences 
between them in the two points mentioned, vzz., in the origin 
of the peribranchial sacs and the first buds. 
As regards Goodsiria we may assume that the embryonic 
development is essentially like that in Botryllus. For my own 
part I fully expect that this will prove to be the case. How- 
ever, we are by no means certain of it, and even if we were we 
should be far from clear sailing as regards the origin of the 
peribranchial sacs of the embryo, since Pizon insists that they 
arise from the endoderm of Sotry/lus, and Garstang is inclined 
to accept his conclusion. If the peribranchial sacs of Perophora 
arise from the ectoderm as they do in Clavelina, and 7f the 
stolonic septum of the first bud of Perophora arises from the 
pharynx as it does in Clavelina, and 7f the first bud of Goodstria 
arises like the first bud of Botryl/us, and zf the peribranchial 
sacs of Botryl/us arise from the ectoderm, then weighing all 
the evidence together, anatomical as well as developmental, it 
seems to me that the budding in the one genus is genetically 
independent of the budding in the other. 
This view I have practically expressed before ('95a), in con- 
tending that the Compound Ascidians have had a double 
origin from the Simple ones. 
But, as already said, I regard it as necessary that the above 
formidable array of ifs should be gotten out of the way before 
the discussion can profitably be carried farther. 
And now concerning the “epicardiac tubes”’ that are of so 
much importance in connection with Tunicate budding. I have 
elsewhere (95) said, regarding the origin of the pericardial 
vesicle in Goodsiria, that an epicardium is here present “as in 
Botryllus.’ As will be readily seen by comparing Figs. 18 and 
19, Pl. XIII, with, for example, the woodcut given by Pizon 
(93), page 30, of Botryllus, there can be no doubt that the 
posterior extremities of the peribranchial sacs in my figures of 
Goodsiria are the same as those marked g.v. by Pizon. The 
only difference in the two cases is in the size. The two 
pouches are much longer in Botry//us than in Goodsiria. Both 
Pizon ('93) and Garstang (94) regard the structures in Botryllus 
