398 W. G. Van Name — Bermuda Ascidians. 



Family ASCIDIIDiE Herdman, 1880. 



Body usually sessile, rarely pedunculated. Branchial aperture gen- 

 erally S-lobed ; atrial generally 6-lobed. Test gelatinous or cartila- 

 ginous, rarely chitinous or horny. 



Branchial sac without folds. Internal longitudinal bars present 

 and usually papillated. Stigmata straight or curved. Tentacles 

 simple. 



Alimentary canal on one side of the branchial sac, sometimes 

 extending postei'iorly beyond it to a slight extent. 



Reproductive organs placed close against or within the intestinal 

 loop. 



Genus Ascidia Linn., 1767. 



Body attached, sessile, rarely pedunculated ; surface bare or 

 incrusted with sand. Branchial and atrial apertures placed far 

 apart, usually 8-lobed and 6-lobed respectively. 



Test cartilaginous, membranous, or gelatinous, soft or hard, usually 

 crowded with bladder-cells. 



Branchial sac sometimes minutely plicated. Stigmata straight. 

 Internal longitudinal bars generally papillated. 



Dorsal lamina a continuous membrane, which may be provided 

 with transverse ribs or with teeth. It is continued behind the oeso- 

 phageal aperture. 



Alimentary canal and reproductive organs on the left side of the 

 body. 



Ascidia atra Lesueur. 



Ascidia atra Lesueur, Descriptions of several new species of Ascidia, Journ. 



Acad. Nat. Sci. of Philadelphia, vol. iii, pt. 1, p. 2, pi. i, fig. 2, 1823. 

 Ascidia nigra Sav.; Herdman, Prelim. Eep. Challenger, Proc. Royal Soc. 



Edinb., vol. ix, pp. 460 and 466, 1880. 

 Phallusia atra Lesueur ; Traustedt, Vestindiske Ascidiae Simplices, Aftryk af 



Vidensk. Meddel. fra den naturh. Foren. i Kjobenhavn, p. 22, pi. iv, fig. 



6, and pi. v, fig. 17, 1881. 

 Ascidia nigra Sav.; Herdman, Eep. Yoy. Challenger (Zool.), vol. vi, part 



xvii, p. 210, 1882. 

 Ascidia atra Lesueur ; Sluiter, Tuniciers recueillis dans la Mer des Antilles, 



etc., M£m. Soc. Zool. de France, vol. 11. p. 7, 1898. 



Plate LXIII. Figures 138 and 139. 



The body is only moderately elongated, with large, anteriorly 

 directed siphons which often have more than the normal number of 

 lobes to the apertures. It is usually attached by the posterior end, 



