510 



UROCHORDA 



While the Ascidians in the narrow sense indude all the 

 more typical Tunicates, there are two other sets, few in 



Fig. 291. — " Nurse " of Doliolum mulleri. — After Uljanin. 



/., Inhalant, £., exhalant aperture ; C, ciliated band round 

 pharynx (P.) ; En., endostyle ; 0., " otocyst " ; A''., nerve- 

 ganglion ; H., heart ; CE., assophageal opening ; D., stomach ; 

 A., anus ; CI., cloaca ; D.O., dorsal organ ; M., muscle bands. 



Fig. 292. — Sexual individual of Doliolum mulleri. — 

 After Uljanin. 



G., gonads ; B., gill-slits ; other letters as before. The unlettered 

 reference line points to the stomach. 



number both as regards genera and species, but of great 

 theoretic importance. 



