REPORT ON THE TUNICATA. 81 



general length of the one hundred and forty sjiecimens in that gathering, and of the 

 one hundred and fifty specimens collected in the South Atlantic, on March 3-5, 1876, is 

 1 cm., exclusive of the posterior processes. These processes measure about 5 or G mm. 

 in length, relatively as long as in Traustedt's variety fiagelliftra. In man}- of the 

 specimens obtained March 3-5, 1876, the distal portions of the posterior processes arc of 

 an opaque white colour. When examined under the microscope they are seen to 

 have a yellowish tint, and to be nodulated on the surface (PI. VIII. fig. 1). 



Some of the smaller specimens {e.g. those obtained in the South Atlantic on 

 February 12, 1876) have no chains of embryos, although in all other respects they 

 resemble the larger specimens ; while other still smaller specimens (about 4 mm. in 

 length) have the posterior processes of the body exceedingly short (PL YIII. fig. 2). 

 Some of these specimens have serrated ridges at the anterior end of the body. 



In these young specimens the proliferation of the ectoderm to form the young test 

 cells is particularly well seen (PI. VIII. fig. 6). The test cells are most abundant at 

 the growing points of the test processes. The ectoderm cells are mostly stellate 

 (PI. VIII. fig. 7). In those specimens where the test is slightly echinated in places, 

 a test cell in process of becoming a small bladder cell is seen at the base of each of the 

 small spines (PI. VIII. fig. 5, hi). 



Turnins now to the a^sreo-ated form, we find that the average length is about 

 6 mm. ; while in the large gathering obtained in the South Atlantic on February 12, 

 1876, the specimens vary from 3 mm. to 10 mm. 



The shape of the aggregated form also varies. The specimens obtained on February 

 28, 1876, are more angular in shape than usual. The three specimens collected 

 in the Southern Ocean, on December 19, 1873, have bifid ends, recalling the condition 

 found in some specimens of the aggregated form of Saljja runcinata-fusiformis (see 

 p. 76 and PL VI. fig. 6). 



In some other specimens, again, especially in some of those collected off" the coast 

 of Australia, on April 2, 1874, the posterior end of the mantle runs out into a tapering 

 process (PL VIII. fig. 4), in place of being simply rounded off" behind the nucleus, as 

 is shown in Traustedt's figures. In other specimens from the same locality, however, 

 the posterior end of the mantle is in the normal condition. 



This is the species described by Professor M'lntosh,^ under the name Salpa spinosa. 

 Otto, as being present along with Salpa runcinata-fusiformis in great abundance in 

 some parts of the Hebrides. 



Salpa nitida, n. sp. (PI. VIII. figs. 11-15). 



External A'pp>earancc. — The body is of an elongated ovate shape, and has no 

 processes. Length 9 mm., breadth 5 mm. 



^ Journ. Linn. Soc. Load. (Zool.), vol. is. p. 41, 18G8. 



(ZOOL. CHALL, EXP. — PART LXXVI. — 1888.) Gggg 11 



