No.1.] BUDDING IN GOODSIRIA AND PEROPHORA. 217 
as homologous with the epicardium of Clavelina, Distaplia, 
Fragrotdes, and other species. 
Thus the last-named author says: ‘In spite, therefore, of 
the final difference of position between the epicardial (or peri- 
visceral) sacs of the Botryllidae and the epicardial tubes of 
Distaplia or Clavelina, there can be no doubt, as Pizon has 
maintained, that there is an exact homology between the two 
structures.’ Nevertheless, there is, in my mind, a very grave 
doubt that the structures in Goodstria, which are certainly the 
same as those called epicardial sacs in Botryllus, have anything 
whatever, either morphologically or physiologically, to do with 
the epicardial tubes of Clavelina. 
It is well known from the investigations of Seeliger and 
Van Beneden et Julin that the epicardial tubes of C/avelina 
arise from the branchial sac, and they arise in the same way in 
Glossophorum (Hjort, '95) and Fragrotdes (Maurice, ’gs). As 
Pizon and Garstang contend, the mere fact that the structures 
arise from the branchial sac of some species, and from the peri- 
branchial sacs in others, would not in itself present any diffi- 
culty against regarding them as genetically homologous (and I 
take this to be the kind of homology that these authors mean, 
for I do not suppose they recognize any other kind). But 
this view would have to regard it as proven that the branchial 
and peribranchial sacs both arise from the endoderm in the 
embryozooid ; and this can certainly not be granted as our 
knowledge now stands. 
As previously said, Pizon claims that such is their origin in 
the Botryllus embryo; and Garstang is inclined to support the 
same view. Should it finally be established that this is in 
reality the case, then, so far as this much of the evidence is 
concerned, the structures may be homologous in Botryllus and 
Clavelina, and of course in Goodsiria, also, if its embryonic 
development here is similar to what it is held by Pizon to be 
for Botryllus ; but this is still to be shown. 
But now it being conceded that, so far as concerns the 
evidence yet in hand relating to the origin of these structures, 
they may fosszbly be homologous, we must still consider what 
the evidence of their destiny is. 
