origin from the inner vesicle has been completely lost, as 

 they do not appear until quite a late stage, and then merely 

 as prolongations backi^^ard of the lateral portions of the pe- 

 ribranchial cavity, after the latter have been entirely cut 

 off from the inner vesicle. This would, therefore, be a 

 still more modified condition than that which is found in Bo - 

 tryllus . 



Pizon (I.e., page 105) makes the statement, which 

 is not, however, illustrated by figures, that he has confirm- 

 ed on the buds of Perophora Listeri the results of Kowalewsky 

 (13: Amaroucium proliferum ) and of Van Beneden and Julin (33: 

 Glavelina Rissoan-t) in regard to the origin of the epicardial 

 tube. "Ce tube", he says, "resulte bien de la reunion de 

 deux petits diverticules qui naissent a droite et a gauche 

 du sac branchial et qui s'isolent conpletement de celui-ci 

 a un moment donne . " Such a description is not in the slight 

 est accord with my obser-'ations, and if an epicardial tube 

 arises in this manner in the buds of the European Perophora , 

 it certainly does not in Perophora viridi s . 



The Branchial Sac or Pharynx. That portion of the 

 original inner vesicle, which is left after the separation of 

 the peribranchial cavity, becomes the pharynx. At its ante- 

 rior end it finally opens to the exterior through the bran- 

 chial orifice, and after the appearance of the gill-slits it 

 comjnunicates with the peribranchial cavity, w..ile posteriorly 

 it leads off into the digestive tract. 



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