GENERAL NOTES ON TUNIC ATA. 



407 



respiratory current as in the Ascidians, and the gill-slits may be few in 



N M 



DO 



Fig. 176A. — " Nurse" of Doliohim m&lleri. —After Uljanin. 



I., inhalant, E., exhalant aperture; C, ciliated band round 

 pharynx (P) ; En., endostyle ; O., otocyst ; N., nerve-gang- 

 lion; H., heart; CE., (esophageal opening; D., stomach; A., 

 anus; CI., cloaca; DO., dorsal organ ; M., muscle bands. 



number, or, as in Salpa, may be represented by two large holes in the 

 walls of the pharynx. Further, the hermaphroditism is modified by the 



Fig. 176B. — Sexual individual ot Doliohnn miilleri. — 



After Uljanin. 



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



reference line points to the stomach. 



occurrence of very marked protogyny, and the ova are never numerous 

 — in Salpa each sexual individual usually produces only one. 



