BRITISH TUNICATA. 



Family I. ASCIDIADJE (continued). 

 G-enus 2. CIONA (Savigny) Fleming, 1828. 



[Ascidia (pars) LINN.EUS Syst. Nat. ed. 12, I, pt. 2 (1767), 



p. 1087.] 

 Phallusise donas SAVIGNY Mem. Aniui. sans Vert. pt. 2 



[1816], p. 169. 

 dona FLEMING Brit. Anim. [1828], p. 468; [HANCOCK 



in Ann. Nat. Hist. (4) VI (1870), p. 364]. 



Body subcylindrical, gelatinous, very contractile, 

 attached more or less by the right side. Apertures 

 terminal or nearly so, and not far apart ; the branchial 

 8-lobed, the atrial* 6-lobed; with conspicuous ocelli. 

 Test soft, smooth, and flaccid. Mantle with strong, 

 longitudinal, muscular bands. Tentacular filaments 

 numerous and slender, linear. Branchial sac elon- 

 gated, [narrow,] not reaching to the bottom of the 

 mantle ; the meshes rectilinear with papillae at the 

 intersections. Oral filaments [replacing the lamina] 

 numerous. Stomach, intestine, and reproductive organs 

 extending below the branchial sac. 



The genus Ciona may be distinguished from Ascidia 

 by the softness and great contractility of the test, and 

 by the stomach and intestine being situated below the 

 branchial cavity, in this respect approaching to the 



* The term " anal " used by the authors has in this volume been altered 

 to " atrial" when it applies to the tube and its aperture by which the atrium 

 communicates with the external medium. 



II. 1 



