tubes of other Ascidians, and states (I.e., page 29), that 

 "la formation de cette cavite peri viscerale n 'est pas secon- 

 daire ©t qu'elle s'est annoncee, des le debut, par deux pe- 

 tits diverticules posterieurs de la vesicule primitive, en 

 niemetenps que les diverticules anterieurs correspondants qui 

 engendreront la cavite peribranchiale . " 



These perivisceral diverticula, however, differ 

 from the epicardial tubes of Clavelina , Distap lia and the 

 Polycl inidae in that they communicate with the cloacal cavi- 

 ty. 



Hjort (I.e., page 594) states, that the "einheit- 

 liche Peribranchialblase sich nun derart weiter entwickelt, 

 das sie nicht nur den Abscnnitt des Kiemendarnies , sondern 

 den ganzen Darmtractus unwachst", and Salensky (27), who ac- 

 cepts the conclusion of Pizon as to the homology of the peri- 

 visceral diverticula, thinks that Hjort evidently saw the 

 'epicardial sacs' in Bo try 11 us, but failed to recognize them 

 as such. Salensky believes that the connection of the 'epi- 

 cardial sacs' with the cloaca in Botryllus , must be regarded 

 as a result of the early separation of the peribranchial ca- 

 vity from the inner vesicle. 



In the light of these considerations it is possible 

 that the posterior extensions of the peribranchial sacs, 

 which I have described as arising in the buds of Perophora 

 viridis ,are likev/ise homologous with the epicardial tubes of 

 other Ascidians. It is to be remembered, however, that if 

 such be the ease, which I think very doubtful, their direct 



