ZOOLOGY 



SECT. 



is cask-shaped, surrounded, as by hoops, by a series of annular 

 bands of muscular fibres (mus. bds.). The oral and atrial apertures 

 (or. ap., atr. ap.), instead of being situated near together at the same 

 end of the body, are placed at opposite extremities, and the 

 relations of the various organs have undergone a corresponding 



rnit,s.bd.s 



air a. ft 



FIG, 735. Doliolum. Diagram of the sexual form. atr. ap. atrial aperture surrounded by 

 lobes ; atr. cap. atrial cavity ; d. tbc. dorsal tubercle ; end. endostyle ; ht. heart ; int. intestine ; 

 mus. bds. muscular bands ; ne. gn. nerve-ganglion ; or. ap. oral aperture ; oy. ovary ; peri. M. 

 peripharyngeal band ; ph. pharynx ; stiff, stigma ; stom. stomach ; test, testis. (After 

 Herdman.) 



modification. The test is thin and transparent. Surrounding 

 each opening is a series of lobes the oral and atrial lobes in 

 which there are sense-organs ; and the first and last of the muscular 

 hoops serve as sphincters for the two orifices. The oral aperture 



or.ap 



branch n.e.ffn 



FIG. 736. Salpa democratica, asexual form, ventral view. air. ap. atrial aperture ; branch. 

 dorsal lamina ; end. endostyle ; ht. heart ; mus. bds. muscular bands ; ne. gn. nerve-ganglion ; 

 or. ap. oral aperture ; proc. processes at the posterior end ; sens. org. sensory organ (ciliated 

 funnel and languet) ; stol. stolon. (After Vogt and Jung.) 



leads into a wide pharyngeal sac (ph.) occupying at least the 

 anterior half of the body ; the posterior wall of the pharynx alone 

 is usually perforated by stigmata (stig.). An endostyle (end.) is 

 present, and a peripharyngeal band ; but there is no dorsal lamina, 

 liolum moves through the water by the contractions of the 



