62 



B1JIT1SH TUNICATA. 



gang-lion. And we thus find in the nervous element a cor- 

 roboration of the above suggestion as to the homological 

 relation of the branchial sac. 



v.d. 



FIG. 12. Ascidia mentula. i. Intestine, v.d. Vas deferens. od. Oviduct. 

 ch. Blood-channel laid open. This channel lies immediately below the 

 reproductive channels and between them and the mantle. 



