VI PREFACE. 



no use to me, or to any other naturalist, in systematically 

 classifying the Cirripedes. 



Previously to Mr. Gray suggesting to me the present 

 Monograph, Mr. Stutchbury, of Bristol, had offered to 

 intrust to me his truly beautiful collection, the fruit of 

 many years' labour. At that time I refused this most 

 generous offer, intending to confine myself to anatomical 

 observations ; but I have since accepted it, and still 

 have the entire splendid collection for my free use. 

 Mr. Stutchbury, with unwearied kindness, further sup- 

 plied me with fresh specimens for dissection, and with 

 much valuable information. At about the same period, 

 Mr. Cuming strongly urged me to take up the subject, 

 and his advice had more weight with me than that of 

 almost any other person. He placed his whole mag- 

 nificent collection at my disposal, and urged me to treat 

 it as if it were my own : whenever I told him that I 

 thought it necessary, he permitted me to open unique 

 specimens of great value, and dissect the included animal. 

 I shall always feel deeply honoured by the confidence 

 reposed in me by Mr. Cuming and Mr. Stutchbury. 



I lie under obligations to so many naturalists, that I 

 am, in truth, at a loss how to express my gratitude. 

 Mr. Peach, over and over again, sent me fresh specimens 

 of several species, and more especially of Scalpettum 

 vulgar e, which were of invaluable assistance to me in 

 making out the singular sexual relations in that species. 

 Mr. Peach, furthermore, made for me observations on 

 several living individuals. Mr. W. Thompson, the dis- 

 tinguished Natural Historian of Ireland, has sent me the 



