X PREFACE. 



which they placed the collections of the Jardin des Plantes at my disposal, and for the 

 opportunity thus afforded me of critically examining the authentic specimens of 

 Lamarck, as well as other interesting hydroid collections in the museum. To 

 Professor Stossich, of Triest, I am also indebted for an opportunity of examining the 

 collection of hydroids in the museum of that town, one of the best collections of these 

 animals contained in any Continental museum which I have been able to consult. 



To Professor Paolo Panceri, of the University of Naples, my thanks are especially 

 due, not only for the liberal way in which he placed in my hands specimens for 

 investigation, but for the valuable assistance I received from him in the examination 

 of the Neapolitan coast. 



To my friend Professor Schiff, of Florence, I owe my hearty acknowledgments 

 for aid in consulting the museum of that city, and for many other ways in which he 

 has facilitated my researches. 



To the Marquis Giacomo Doria, who, in the disinterested love of science, has 

 devoted his time and property to the advancement of natural history, pursued, at the 

 sacrifice of health, amid the malaria of East Indian jungles, and has thus added 

 another laurel to those which have already made the name of Doria illustrious in the 

 annals of the great Genoese Republic, as well as to Dr. Gestro, his assistant, and to 

 Professor Trinchesi, of the University of Genoa, I am indebted for much kindness, and 

 for valuable guidance to the zoological localities of the Gulf. 



To Dr. Giglioli, of Florence, I owe the opportunity of inspecting an extensive 

 collection of drawings in which he records many important observations made on 

 hydroid planoblasts and other pelagic forms met with during the circumnavigatory 

 voyage of the " Magenta," which he accompanied as assistant-naturalist. 



Dr. Du Plessis, of Nice, who has made the hydroids of the neighbouring coast 

 a subject of special study, and has been singularly sucessful in keeping them in a 

 healthy state in his vivarium, kindly acted as my guide to various hydroid localities 

 with which he had become familiar in the beautiful bay of Villafranca ; while I am also 

 under much obligation to Professor MecznikofF, of St. Petersburgh, who happened to 

 be at the same time residing at Villafranca, where he was engaged in researches on the 

 lower animals of the bay, and where he communicated to me some of the important 

 results to which he had arrived. 



To Professor Van Beneden, of Louvaine, and to the late venerable Professor 

 Sars, I am indebted for presentations of their many important memoirs, and for the 

 communication of specimens, while my thanks are also due to Professor Agassiz and 

 to Mr. Alexander Agassiz, as well as to Professor Kolliker and to Professor Haeckel, 

 for copies of many valuable memoirs bearing more or less directly on hydroid zoology. 

 And still further, I must express my obligations to Professor Costa, of the 

 University of Naples ; to Sig. Pillppo Trois, of Venice ; to Professor Savi, of Pisa ; 

 to Professor Oscar Schmidt, of Gratz ; to Dr. Antoine Pritsch, of Prague ; to Dr. 



