Yj Preface. 



The observations recorded in this book extend over a space of nearly three 

 years, and were made for the most part at the Zoological Station of Naples, during 

 my occupancy of the Oxford Biological Scholarship for two years, and of the British 

 Association Table for one year. 



To Professor Dohrn I ani more deeply indebted than I can well express for 

 the continuons support which he has given me in my work, and for the many 

 suggestions which he has offered relatively to the morphology of my group. 



To the whole staff of the Zoological Station and partieularly to Professor 

 Mayer nnder whose province my work especially carne, I am deeply obliged for 

 their friendly attention to my needs. 



Of the many friends and acquaintances who have helped me I would mention 

 especially Dr. H. J. Hansen, who, during my visit to Kjòbenhavn, introduced me 

 to the riches of the collection under his charge, and put many rare specimens at 

 my disposai, the value of which to my work has been very great. Dr. W. Calman, 

 of the British Museum, has not only assisted my examination of the specimens 

 under his charge, but has materially helped me in acquiring what I believe are 

 just views of the morphological relationship of the Rhizocephala to normal Cirri- 

 pedes. To Dr. Duncker I am indebted for specimens and manuscript notes which 

 are considered in the proper place, while Mr. Punnett kindly gave me two spe- 

 cimens of Anelasma squalicola which have been of great use to me, Mr. Crossland 

 some interesting specimens from the Red Sea, and Prof. D'Arcy Thompson a spe- 

 cimen of the rare form Sylon. 



New College, Oxford, August 1906. 



