XII 



PHYLUM CHORPATA 



3'5 



vertical in position ; those of the same row are placed close together, 

 separated only by narrow vertical bars ; neighbouring rows are separated 



or.ap 



lent 



alrap 



plr. 



test 



-mant 



FIG. 185. Dissection of Ascidia from the right-hand side. The greater part of the 

 test and mantle has been removed from that side so as to bring into view the re- 

 lations of these layers and of the internal cavities, and the course of the ali- 

 mentary canal, etc. an. anus ; atr. cip. atrial aperture ; end. endostyle ; gon. 

 gonad ; gonod. gonoduct ; hyp. hypophysis ; hyp. d. duct of hypophysis ; want. 

 mantle ; ne. gn. nerve-ganglion ; ces. ap. aperture of oesophagus ; or. ap. oral 

 aperture ; ph. pharynx ; stem, stomach ; tent, tentacles ; test, test. (After 

 Herdman.) 



by somewhat thicker horizontal bars ; in all of these bars run blood- 

 vesselsl 



