Preface. 



The group of parasitic Cirripedes monographed in this book has engaged the 

 attention of many celebrated naturalists since the time of Cavolini, and in com- 

 paratively recent years has formed the subject of a keenly contested controversy: 

 it may therefore seem a bold step for an unknown writer to enter the field with 

 a monograph which to many will seem to affect the pretension without attaining 

 the reality of completeness. 



But I cannot disguise from myself, and I have neither the wish nor the 

 power to disguise from other people, the many respects in which my work 

 not only falls short of completeness but has been entirely baffled by difficulties 

 of observation and reasoning; and perhaps the best plea I can put forward for 

 avoiding a too harsh criticism is that my very lack of completeness and finality is 

 in part due to the many curious facts which my work has partially brought to 

 light but which will require future independent investigations to fully clear up. 



Not to mention a number of observers who have laid the basis of our 

 knowledge of the Rkizocephala, we owe most perhaps to the two contemporary 

 French naturalists, Professors Delage and Giard, to the former for. his work on 

 the anatomy and life-history of Sacculina carcini, and to the latter for his inter- 

 esting observations on the effect of the parasites on their hosts. It is a matter 

 of regret that these two authors are unable to agree upon many fundamental questions 

 in this subject, but I trust that the record of my observations made under a deep 

 sense of obligation to their work, may, without escaping their criticism, engage 

 their impartial consideration. 



There remains for me in this preface the duty of acknowledging the support 

 of institutions and the generosity of friends, without Avhose help I could not 

 have undertaken this work. 



