I: K PORT ON THE TUNICATA. 



!*.-> 



Ascidiid.e. 



Dorsal lamina present 

 as a membrane. 



Dorsal lamina present in the 

 form of laiiKuets. 



Branchial sac divided 

 into regular 

 meshes. 



Branchial sac an 

 irregular 

 network. 



Illjpollljtlliils. 



Test soft and 



more or less 



flexible. 



Ascidia. 



Test hard, 



very thick 



and stiff. 



Pachyehlaena. 



Stigmata 

 straight. 



Stigmata 

 curved. 



Test un- 

 modified. 



Intestine on 



left side of, 



and posterior 



to, branchial 



sac. 



Ciona. 



Intestine on 

 right side of 

 branchial sac. 



Abyssascidia. 



Test having 

 the anterior 

 part modified 

 so as to form 



a covering 

 over the bran- 

 chial and 



atrial 

 apertures. 



Rhtidoximia. 



Test modified 

 into horny 

 plates. 



Chelyosoma. 



Test more or 

 less soft and 

 gelatinous. 



Body 

 pedunculated. 



( 'orynascidia. 



Body 



sessile. 



( ;>,f lla. 



The family may be broken up, as seen below, into three groups according to the 

 structure of the branchial sac, but this is not altogether satisfactory, since it involves 

 the separation of Abyssascidia from its near allies Corolla and Covynascidi<< ; otherwise 

 it seems the most natural arrangement possible 



AsCIDIIDiE. 



Branchial sac with no internal longitudinal bars. 



Hypobytuinx. 



I 

 Hypobythiu . 



I nternal longitudinal bars pri 



Stigmata Btraij lit. 



I 



ASI ll'I.V.E. 



I 



Ciona. 



Ascidia. 



Pachyehlaena. 



Rhodo8oma. 



Abyssascidia. 



Stigmata curved. 



I 

 CoRi'i.r.ix.K. 



I 



i ! 



Corn 

 Chelyosoma. 



