PLATE XXXI. 



Figs. 1-3. Ascidia placenta, Herdinan. 

 Figs. 4-S. Ascidia meridionalis, Herdman. 



Fig. 1. Ascidia placenta, seen from the right side ; natural size. 



Fig. 2. Part of the branchial sac of Ascidia placenta, seen from the inside ; magnified 



(Hartn., obj. 4). 

 Fig. 3. Part of the dorsal lamina of the same species ; magnified (Hartn., obj. 4). 

 Fig. 4. Ascidia meridionalis, seen from the right side ; natural size. 

 Fig. 5. Part of the branchial sac of Ascidia meridionalis, seen from the outside, and 



showing the attachment of one of the "connectives" (.«.) to a transverse 



vessel ; magnified (Hartn., obj. 4). 

 Fig. (3. Part of the same branchial sac, seen from the inside ; magnified (Hartn., obj. 4). 

 Fig. 7. Part of the dorsal lamina of Ascidia meridionalis; magnified (Hartn., obj. 4). 

 Fig. 8. The dorsal part of the anterior end of the same branchial sac, showing the dorsal 



tubercle (d.t.), the prsebranchial zone with muscle bands showing through, 



and three of the tentacl°<s one long (tn.) and two short (in/) ; magnified 



(Hartn., ol>j. 4,. 



