THE 



VOYAGE OF H.M.S. CHALLENGES 



ZOOLOGY. 



REPORT on the Tunicata collected during the Voyage of H.M.S. 

 Challenger during the years 1873-76. By William A. Herdman, 

 D.Sc, F.L.S., F.R.S.E., Professor of Natural History in University 

 College, Liverpool. 



PART I.— ASCIDI.E SIMPLICES. 



PREFACE. 



This collection of Tunicata, entrusted to me for description by the late Sir C. Wyville 

 Thomson, 1 was placed in my hands early in May 1879. As most of the specimens 

 were in muslin bags packed in large bottles, it was difficult to form a correct idea of the 

 size of the collection. When unpacked and arranged roughly in species it proved to be 

 much larger than had been at first estimated. Since then I have several times received 

 from Mr. Murray bottles of Tunicata which had been accidentally included in other collec- 

 tions, and specimens which had been overlooked in sorting out the different groups. The 

 pelagic forms taken in the tow-net (including the Pyrosomidae, the Appendiculariidaa, and 

 the Thaliacea) did not reach me till some time afterwards. 



My first object was to separate the collection of fixed Tunicata into Simple, Social, and 

 Compound Ascidians. I then commenced to work through the first two of these groups in 



1 I wish here to record my deep sense of indebtedness to Sir Wyville Thomson, for having given such an 

 important piece of work into my charge, and for the ever ready and valuable advice with which he aided me during 

 the first part of my investigations. 



(ZOOL. CIIALL. EXP. PART XVII. — 1882.) E 1 



