190 Southern Cross, 



V I. TUNICA T A. 



By W. a. HEEDMAN, D.Sc, F.H.S. 



(l^lates XIX-XXIII.) 



This collection does not contain many species, but some of the 

 specimens are of very large size. Unfortunately some of them are 

 in very bad condition, and none are really well preserved. Even 

 when refinements of killing and fixing are impossible it should be 

 easy for all collectors of Tunicata to make simple incisions through 

 the test into the interior of the animal — whether it be a simple 

 Ascidian or a colony — before dropping the specimen into alcohol, and 

 that makes a very great difference in the condition of the internal 

 organs after preservation. However, in some of the present cases, 

 from the ragged appearance and the broken-down condition even at 

 the surface of the animal, I am inclined to think that no precautions 

 and care would have availed, as the specimens were probably dead 

 and decomposing colonies when collected. 



Although our knowledge of the Antarctic Tunicate fauna is very 

 limited, still we know that the Southern seas generally have a rich 

 Tunicate fauna. Quoy and Gaimard long ago remarked, " La 

 Nouvelle-Hollande, dans sa partie sud, et la Nouvelle-Zelande, sont 

 les lieux de predilection des Ascidies en general ; " and the Aus- 

 tralian fauna includes over 180 known species of Ascidians, a greater 

 number than that known from the shores of North-West Europe, a 

 corresponding coastal area in the northern hemisphere, and the one 

 that has probably been most exhaustively worked up. The south 

 coast of Australia is in about 40° south latitude. Whether species 

 remain as abundant as we go still further south we do not yet know ; 

 but on the shores of Kerguelen Island (about 50° south latitude) and 

 in the Straits of Magellan (about 55° south latitude), not only are 

 species of Ascidians numerous, but they abound in individuals, and 

 moreover are, as a general rule, of large size. Between latitudes 40° 

 and 55° S. the ' Challenger ' obtained twenty-eight species of simple 

 Ascidians and thirty-nine species of compound. At far southern 

 stations such large and remarkable forms as Ascidia challengeri, 



