X. INTRODUCTION. 



Since the publication of the Keports of the "Challenger' 

 Expedition, however, a number of species of Tunicata have 

 been described from Australian seas by Sluiter, Traustedt, 

 and others. Dr. C. Ph. Sluiter, while resident in the Dutch 

 East Indies, published a most important series of papers in 

 which he described over 30 species of Tunicata from the 

 seas of the Malay Archipelago. It may be a question 

 whether such localities as the Island Billiton, where Sluiter 

 obtained some of his species, can be considered as coming 

 within Australian seas ; but there can be no question but 

 that Thursday Island and Torres Straits, where Semori 

 collected the specimens described by Sluiter in his most 

 recent papers, must be included. These comprise nearly 30 

 species of Ascidiacea, both Simple and Compouud. I 

 believe it will add considerably to the completeness and 

 usefulness of this catalogue if I add a record of all such 

 known Australian species in their proper systematic positions 

 at the end of each family, but distinguished by being enclosed 

 in square brackets [ ] . 



The method of description of a Simple Ascidian which I 

 adopted in my Keports upon the "Challenger'' collection 

 were suggested by the anatomical notes given by Albany 

 Hancock in his last paper,* and have been almost univer- 

 sally followed by writers since. The method consists in 

 describing the external appearance under the heads of shape, 

 colour, size ; then the characters of test and mantle ; then 

 the structure of the branchial sac, endostyle, dorsal lamina ; 

 the number, arrangement, and form of the tentacles, and 

 the condition of the dorsal tubercle ; then anything note- 

 worthy in regard to the alimentary canal and the reproduc- 

 tive viscera. I believe if we had these details and the 

 necessary figures in regard 1o all the named species of 

 Tunicata there would be no difficulty in assigning to each 



* Anatomy and Physiology of the Tunicata. Journ. Linn. Sot'., Zoul., vol. ix., \>. 309. 



