IO THE APPENDAGES., ANATOMY, AND RELATIONS OF TRILOBITES. 
In Part IV are included somewhat detailed descriptions of a few of the best specimens 
of Triarthrus and Cryptolithus. Professor Beecher, while an observer of the minutest 
details, believed in publishing only the broader, more general results of his investigations. 
This' method made his papers brief, readable, and striking, but it also resulted in leaving in 
some minds a certain amount of doubt about the correctness of the observations. In a mat- 
ter so important as this, it has seemed that palaeontologists are entitled to the fullest possible 
knowledge of the specimens on which the conclusions are based. The last part is, therefore, 
a record of the data for the restorations of Triarthrus and Cryptolithus. 
The illustrations in the plates were nearly all made by or under the supervision of 
Professor Beecher, as were also text figures 45 and 46. 
In conclusion, I wish to express my thanks to Mrs. Charles E. Beecher for the use of 
drawings which were the personal property of Professor Beecher; to Doctor Charles D. 
Walcott for photographs of the limbs of Calymcnc, and for his kindness in sending me the 
slices of trilobites from Trenton Falls and specimens of Neolenus and Triarthrus; to Doctor 
R. V. Chamberlin for suggestions and criticisms in regard to the relationship of trilobites 
to Insecta, Arachnida, Chilopoda, and Diplopoda; to Mr. Samuel Henshaw, Director of the 
Museum of Comparative Zoology, for permission to use the time which has been devoted to 
this work; and to Miss Clara M. Le Vene, for assistance in the preparation of the manu- 
script. My greatest debt is to Professor Charles Schuchert, to whom the work owed 
its inception, who has assisted in many ways during its prosecution, and who read the manu- 
script, and arranged for its publication. To him I can only express my warmest thanks for 
the favors which I have received and for the efforts which he has- put forth to make this 
a worthy memorial to our friend and my teacher, Professor Charles Emerson Beecher. 
Harvard University, Cambridge, Mass. 
November, 1919. 
