19(5 THE VOYAGE OF H.M.S. CHALLENGER. 



nerve ganglion (fig. 15), which thus comes to be placed at a considerable distance 

 from the branchial aperture. 



The course of the alimentary canal (PL XXVII. figs. 3, 5 and 6) is very similar to 

 that found in Corella parallelogramma. The narrow oesophagus (PL XXVII. fig. 6, ce.a.) 

 opens near the base of the branchial sac at the dorsal edge, and runs horizontally (the 

 branchial aperture being superior) for a short distance, and then opens into the barrel- 

 shaped stomach (figs. 5 and 6, St.), which has its wall raised externally into about twelve 

 r< mnded longitudinal ridges, and is situated about half-way across to the ventral edge. 

 From the opposite end of this stomach the intestine curves ventrally and slightly upwards, 

 then downwards, and then runs parallel to its first part (PL XXVII. figs. 3, 5 and 6, L), 

 past the stomach and oesophagus, turns upwards, runs past the oesophageal opening, and 

 ends in a prominent anus (figs. 5 and 6, a.) not far from the posteriorly placed atrial 

 aperture. The faeces are brown. 



The genital mass is situated, as is usual in the genus Corella, upon the ventral portion 

 of the intestine, where it turns round posteriorly after leaving the stomach. 



The ovary (PL XXVII. fig. 1G, or.) forms the central part of the genital mass, and 

 the testis occupies the periphery, and consists of pyriform spermatic vesicles (PL XXVII. 

 figs. 16 and 18, t.v.) full of small spherical cells. 



The oviduct and vas deferens emerge from the dorsal and posterior end of the mass, 

 and course along the superior (anterior) margin of the intestine (PL XXVII. fig. 5, g.d.) 

 to their termination. 



One specimen of Abyssascklia wyvillii was obtained to the south of Australia, at 

 Station 160; March 13, 1874 ; lat. 42° 42' S., long. 134° 10' E. ; depth, 2600 fathoms; 

 bottom temperature, 0°"2 C. ; bottom, red clay. 



Ascidia, Linnaeus. 



Ascidia, Linnaeus, Syst. Nat., 12th Edn. 1766. In part. 



Aseidia, 0. F. Miiller, Zoologia Danica. 1780. In part. 



Ascidia, Cuvier, Mem. sur les Ascidies, M6m. du Mus., vol. ii. 1815. In part. 



Phallusia, Savigny, Mem. sur les Anim. sans Vertebres, pt. ii. fasc. 1. 1816. In part. 



Ascidia, Forbes and Hanley, Brit. Moll., vol. i. 1853. In part. 



Ascidia, Alder, Observations on Brit. Tunicata, Ann. and Mag. Nat. Hist., ser. iii., vol. xi. 1863. 



In part. 

 Ascidia, Hancock, On the larval state of Molgula, &c, Ann. Mag. Nat. Hist. ser. iv., vol. vi. 



1870. 

 Ascidia and Ascidiopsis, Verrill, Arner. Journ. of Science and Arts, ser. iii., vol. i. 1871. 

 Ascidia, Heller, Untersuchungen ii. d. Tunicata adriat. Meeres., Abth. 1. 1874. 

 Phallusia, Kupffer, Jahresber. der Commiss., &c. 1875. 

 Phallusia, Traustedt, Oversigt over de fra Danmark, &c, Asc. Simp. 1880. 

 Ascidia and Phallusia, Julin, Becher. sur l'organ. des Asc. Simp. — Sur l'Hypophyse, &c. 1881. 



