REPORT ON THE TUNICATA. 7 



in structure and in life-history between Pyrosoma and Scdpa on the one hand, and 

 between Pyrosoma and the Compound Ascidians on the other. 



In the Eemarks upon Appendicularia and Doliolum, Huxley proved con- 

 clusively that the first of these forms belonged to the Tunicata. It had previously 

 been described by Chamisso as a Ccelenterate, and by v, Mertens as a Pteropod. He 

 also was the first to give a good anatomical description of Appendiculana, and to 

 point out the interest attaching to the persistent tail. For Doliolum he performed 

 a similar service, giving for the first time a thorough description of the structure of 

 this little-known form, and indicating its true position amongst the other Tunicata. 



Interest was now thoroughly awakened in regard to these important forms and 

 their complicated life-histories ; and during the ten years that followed a number of 

 the leading European naturalists produced papers on the pelagic Tunicata. Gegenbaur 

 wrote on Doliolum and on Appendicularia, Krohn on Doliolum, H. Miiller on Salpa, 

 C. Vogt on Salpa, Leuckart on Saljya and Doliolum, AUman on Ap>pendicularia, 

 Kefersteiu and Ehlers on Doliolum, and Huxley on all four genera. 



The great embryological impulse which was given by Kowalevsky's celebrated 

 memoii- on the development of a Simple Ascidian in 1866 did not afl'ect the litera- 

 ture of the pelagic Tunicata so immediately as it did that of the Ascidiacea, and for 

 some years after all the more important papers were on the Simple or the Compound 

 Ascidians. In 1872 appeared Fol's important treatise on the Appendicularians. This 

 is by far the most comprehensive work on the Larvacea that has yet been written, 

 and was the first to give an adequate account of the group as a whole. In 1875, 

 Kowalevsky in one of his admii-able embryological memoirs gave a detailed account of 

 the development of Pyrosoma, confirming and supplementing the previous description 

 by Huxley, who had first discovered the remarkable " cyathozooid," and its relations 

 to the first Ascidiozooids of the colony. Attention was now directed to the Salpidee, 

 and from that time up to the present there has been a more or less continuous series 

 of, in many respects, conflicting accounts of the development, gemmation, and life- 

 history of Salpa. The more important of these papers have been written by Brooks 

 (1875 and 1886), Todaro (1875, 1880, 1882, and 1887), Barrels (1881-82), Seeliger 

 (1885), and especially Saleusky (1877, 1878, and 1882-83). A very useful i:)aper by 

 Traustedt, published in 1885, deals with all the known species of the Salpidaj, dis- 

 cussing their characters, distinguishing them, and reducing their synonymy to order. 



The Cyclomyaria have also been largely investigated during the last five or six 

 years. The complicated life-history of Doliolum has been gradually worked out by 

 the successive papers of Grobben and Uljanin, while the allied form Anchinia has been 

 investigated by Korotneff", Kowalevsky, Barrels, and Wagner, thus bringing our 

 knowledge of the pelagic Tunicata up to its present condition. 



