28 



ZOOLOGY 



SECT. 



fixed, is colonial in one species, and has the oral and atrial apertures 

 towards one end of the body, which is somewhat discoid, with its 

 margin produced into eight tapering processes. It has no eye 



mua.bds e-nd 



or. a/a 



FIG. 727. Salpa democratica, asexual form, ventral view. atr. 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. ory. sensory organ (ciliated 

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



(cf. p. 30). In all probability Octacnemus is more nearly related 

 to the social Ascidians (p. 25) than to Salpa. * 



Pyrosoma (Fig. 729) is a colonial Tunicate, the colony assuming 

 the form of a cylinder, the internal cavity of which, closed at one 



c.c 



p.p 



end. 



FIG. 728. Salpa. Lateral view of a section which is sagittal (longitudinal, vertical and 

 median) in the oral two-thirds, and oblique in the atrial third, at. atrial cavity ; 

 br. branchia ; c. c. ciliated crests on the edge of the branchia ; <. f. ciliated funnel ; d. I. dorsal 

 lip; end. endostyle; ey. eye; gl digestive gland; tjn ganglion; ht. heart; int. intestine; 

 I ;/. languet; mo. mouth; o;s. (esophagus; ;. ap. cesophageal aperture; ph. pharynx; pp. 

 peripharyngeal band ; st. stolon ; st. (behind) stomach ; v. I. ventral lip. (After Dclage and 

 Herouard.) 



end, open at the other, serves as the common cloaca for all the 

 zooids. The oral apertures (Fig. 730, or. ap.) of the zooids are 

 situated on the outer surface of the cylinder on the extremities of 



