lv THE VOYAGE OF H.M.S. CHALLENGER. 
kindly permitted me to make use of them here. They are distinguished by the initials 
“W.B.C.”; while thirty-one of the remaining thirty-six which are marked “ P. H. C.,” 
have been drawn under my own superintendence by Messrs. C. Berjeau, F.L.S., and 
P. Highley. I am very greatly indebted to both these gentlemen for the care and skill 
with which they have performed a difficult and laborious task, one, moreover, involving 
a considerable acquaintance with minute structural details. I am under similar obliga- 
tions to Mr. George West, who lithographed three anatomical plates, and also gave me 
valuable information respecting the specimens from which he had drawn several plates 
foy Sir \yyville Thomson. I have likewise to thank Mr. Black for similar information 
concerning those plates which had been drawn by himself; and also Mr. W. E, Hoyle, M.A., 
of the Challeager Office, for kindly working out the magnification of some of the figures 
upon Mr. Black’s plates. 
i have fucther gratefully to acknowledge much valuable bibliographical assistance from . 
my friends Prof. F. J. Bell, F.Z.8., and Mr. W. P. Sladen, F.L.S.; while my thanks 
are also due to Prof. H. N. Moseley, Dr. P. P. C. Hoek, Mr. H. B. and Dr. G. 8. Brady, 
and to Mr. Edgar Smith, F.Z.8., for kindly identifying various organisms which I had 
found attached to different parts of the Crinoids. 
Prof. Carl Zittel of Munich and Prof. G. Meneghiniof Pisa have been good enough to 
send me several fossil specimens of Rhizocrinus for examination, and I take this opportunity 
of thanking them. But I find it difficult to express my indebtedness to Mr. Charles 
Wachsmuth of Burlington, Iowa, U.S., who is so well known as the leading authority 
upon the Palzocrinoidea. Not only has he frequently sent me for examination very rare 
and valuable specimens illustrating the morphology of the Palzocrinoids and Blastoids, 
but he has repeatedly answered my inquiries in the fullest and most complete manner 
possible. The relations of the Neocrinoids and the Paleocrinoids have been the subject 
of a prolonged discussion between us, extending over more than two years; and it is a 
matter of sincere regret to me that we have been obliged to agree to differ. Time will 
show how far our respective views will need modification. We have approached the 
subject from different sides ; but upon one point we are in complete accordance, viz., the 
desire to find out the truth, whether or not it agree with our own ideas upon the 
subject. Mr. Wachsmuth will shortly publish an explanation of his own position, to 
which I would refer those who are interested in the matter. 
In conclusion, I must express my sincere thanks to Mr. John Murray and to 
Prof. Alexander Agassiz for having entrusted me with the working out of the Crinoid 
collections in their charge, and for their readiness to afford me every possible assistance 
in doing so; while I would pay a heavy debt of gratitude to the memory of the late Sir 
Wyville Thomson. It was my privilege to accompany him and my father in the short 
but eventful cruise of H.M.S. “ Lightning” in the year 1868 and in the “ Porcupine” 
expedition of 1869; and to his kindness and encouragement both then and sub- 
