REPORT ON THE TUNICA TA. 207 



Two specimens were obtained to the south of Kerguelen Island, at Station 150 ; 

 February 2, 1874; hit, 52° 4' S., long. 71° 22' E.; depth, 150 fathoms; bottom 

 temperature, l 0- 8 C; bottom, rock. 



Ascidia meridionalis, Herdman (PI. XXXI. figs. 4-8). 



Ascidia meridional^, Herdman, Prelim. Rep., Proc. Roy. Soc. Ediu., 1879-80, p. 4G5. 



External Appearance. — The shape is somewhat variable ; it is generally oval, the 

 anterior end being rather narrower than the posterior. The posterior end is rounded, and 

 the anterior more or less pointed. The body is flattened laterally, and is attached by the 

 posterior end and part of the left side. The branchial aperture is terminal, at tin- 

 extremity of a large conical process, the apex of which is inclined ventrally and to the 

 right ; the atrial aperture is to the right of, or on the dorsal edge, about one-third of 

 the way down ; it also is on a process, which, however, does not usually project so much as 

 the branchial one ; it is directed dorsally, anteriorly, and slightly to the right ; the lobes 

 of both apertures are distinct. 



The surface is slightly velvety ; otherwise it is smooth, but more or less creased and 

 seamed. The colour is light brown or horn colour. 



Length of the body, about 1 2 cm. ; breadth of the body, about 8 cm. 



The Test is softish, and tears easily, it is from 1*5 to 6 millimetres thick, the left side 

 being thicker than the right. Vascular trunks enter about the middle of the left side, 

 near the ventral margin, and large vessels are seen ramifying on the inner surface, which 

 is smooth and shining. 



TJie Mantle is moderately muscular. 



The Branchial Sac is slightly plicated longitudinally. Three small transverse vessels 

 occur between each pair of large ones. The internal longitudinal bars are strong, and 

 bear short stout papUlee at the angles of the meshes, and also small conical intermediate 

 ones. The meshes are slightly longer transversely than antero-posteriorly, and contain 

 each 6 to 8 stigmata. The stigmata are elongate-elliptical in shape. 



TJie Dorsal Lamina is broad, and is ribbed transversely ; the margin is serrated. 



Tlie Tentacles are simple, filiform, about sixty in number, and placed long and short 

 alternately. 



The Dorsal Tubercle is crescentic in shape, with the horns pointing anteriorly. 



This is a large and well marked species ; the form is more or less oval, the anterior end 

 being the narrower (PI. XXXI. fig. 4). In some of the specimens, however, the shape is 

 a good deal more irregular than in the one figured. The apertures are placed on large 

 conical projections, the sides of which are channelled by the grooves leading down from 

 between the lobes. In one specimen the branchial aperture is only seven-lobed, while 



