I>'TRODUCTION. 
XXI 
Before concluding, I desire to express my obligations to those 
who have aided me in the prosecution of my work. 
To Dr. Gustav Lindstrom I am particularly indebted for much 
friendly advice, as well as for valuable information bearing upon 
questions concerning the nomenclature of certain Swedish fossils, 
which questions could only be decided by one thoroughly con- 
versant with the history of the palaeontological Collections in the 
Royal Museum of Stockholm, which Dr. Lindstrom has under his 
charge. 
To Professor Alpheus Hyatt, of Boston, U.S., I owe many thanks 
for his kindness and liberality in supplying me with a nearly 
complete set of his writings on fossil Cephalopods, of which I have 
made abundant use. 
I am much beholden also to Mr. C. E. Beecher, of Albany, New 
York, who, when he was in London, kindly looked over several of 
the proofs of the Catalogue, and gave me the benefit of his critical 
knowledge of the Xorth-American species of the Xautiloidea. 
To Professor McKenny Hughes and Messrs. Marr and Roberts I 
tender my best thanks for their courtesy in affording me every 
facility for the study of some of the types of British Cephalopods 
contained in the Y'oodwardian Museum, Cambridge ; and I gratefully 
acknowledge similar favours received from Messrs. Newton and 
Sharman, of the Museum of Practical Geology, Jermyn Street. 
I gladly seize this opportunity also of expressing my obligations 
to Dr. Woodward for the valuable and opportune counsel he has 
been ever ready to extend to me. 
My cordial thanks are likewise due to Mr. B. B. Woodward and 
to Mr. G. C. Crick. To Mr. Woodward for the help he has given 
me in the bibliography of the Cephalopoda, and to Mr. Crick for 
having looked through all the proofs, and for many helpful sug- 
gestions, which have contributed in no small degree to the progress 
of the work. 
Loudon, 
December, 188H. 
ARTHUR H. FOORD. 
