REPORT ON THE TUNIC AT A. 195 



The Alimentary Canal is placed on the right side of tin- branchial saCj at the posterior 

 end, and is relatively small. 



The Genitalia form a rounded mass of large size, which lies on the right side of the 

 intestinal loop at the ventral end. 



This interesting form belongs undoubtedly to the Ascidiidse, notwithstanding the 

 large number of lobes around the apertures! These lobes are mostly well defined, but a 

 few are rather indistinct, consequently the numbers might be considered for the bran- 

 chial aperture as either twelve, thirteen or fourteen, and for the atrial as either eight 

 or nine (PL XXVII. fig. 1). The position of the atrial aperture, rather to the right of 

 the middle of the upper surface, is curious ; and the area of attachment being nearer the 

 anterior than the posterior end is also a peculiarity (PL XXVII. fig. 2). The body is 

 depressed, or flattened dorso-ventrally in place of laterally, and as a consequence the edges 

 are formed by the right and left sides, and not by the dorsal and ventral lines. The test 

 is thick and cartilaginous, but soft and very clear ; no vessels nor bladder cells were 

 observed. When the test is removed the body is seen to be very much smaller 1 than the 

 cavity in which it lies (PL XXVII. figs. 3 -and 4, and compare with figs. 1 and 2). It 

 is relatively narrower than when covered by the test, and has the posterior end wide on 

 account of the large postero-dorsal process, at the extremity of which the atrial aperture 

 opens (PL XXVII. fig. 3, at). 



The mantle is very thin, and the muscle bands on its left side and dorsal edge 

 (PL XXVII. figs. 3 and 4, rn.b.) are very strong, and bear a considerable resemblance to the 

 musculature in the genus Corella. The muscle bands on the siphons are fine, and are 

 more numerous on the atrial than on the branchial. They do not form distinct 

 sphincters. 



The branchial sac is of the simplest possible type, having no folds and not being 

 longitudinally plicated, the stigmata being straight, and the internal longitudinal bars 

 bearing no papillae (PL XXVII. fig. 7). The connecting ducts between the transverse 

 vessels and the internal longitudinal bars are long and curved (PL XXVII. fig. 9, c.d.), 

 and support between them the delicate horizontal membranes which hang round the 

 interior of the sac (fig. 7, A.m.). 



The languets are short and blunt somewhat finger-shaped processes, placed close 

 together along the dorsal line, and not all of the same length (PL XXVII. fig. 11, I.). 



The endostyle is normal. The tentacles are very slight, and have a curious arrange- 

 ment. The two pairs placed at the ventral end of the circle, and the two neighbouring 

 isolated tentacles, are shown in figure 12 on Plate XXVI I., and two others from the 

 lateral part of the circle are shown in figure 13. The long tapering dorsal tubercle 

 (PL XXVII. fig. 14, d.t.) lies about three times its own length in front of the elongated 



1 The specimen hail Wen in spirit for about six years when examined. 

 (ZOOL. CIIALL. ESP. — PART XVII. — 1882.) R 26 



