PART I CHAZYAN AND RELATED BRACHIOPODS—-COOPER 5 
dertaking by a member of the U. S. Geological Survey and one from the U. S. 
National Museum, I have enjoyed favors from many of my colleagues in both 
organizations. Dr. Alexander Wetmore, former Secretary of the Smithsonian 
Institution, made possible my numerous field expeditions which furnished the 
major part of the collection. The studies were supported by Dr. R. 5. Bassler, 
the head curator of the department of geology in the National Museum. My 
colleague, Dr. A. R. Loeblich, Jr., helped immeasurably as field companion and 
donor of a large and exceptionally fine collection of Simpson brachiopods. 
Dr. J. B. Reeside, then chief of the section of stratigraphy and paleontology, 
made it possible for me to have and use parts of the collections of the U. S. Geo- 
logical Survey made by Dr. E. O. Ulrich and Dr. Charles Butts. Drs. T. B. 
Nolan and Harry S. Ladd assisted in field trips to the Southwest and West by 
allowing the use of Survey equipment. 
The early stages of the work were greatly facilitated by a grant from the Geo- 
logical Society of America through the Penrose Fund. This grant was made in 
1937 to help me in organizing, preparing, and photographing specimens. Dr. 
Preston E. Cloud, Jr., now chief of the paleontology and stratigraphy branch of 
the Geological Survey, who was the recipient of the grant, prepared and photo- 
graphed most of the materials studied prior to 1938. I wish to express my thanks 
for this grant and my appreciation of the diligence of the grantee. 
In making acknowledgments, I cannot overlook the contributions of my two 
mentors in Ordovician stratigraphy, now deceased. It was originally planned 
that this should be a joint undertaking with Dr. Ulrich, but because of the long 
delay in getting under way Dr. Ulrich voluntarily retired from the project. 
Nevertheless, I will always remember the hours of instruction received from 
him. To Dr. Charles Butts I owe much for his inspired guidance in the Appa- 
lachians. Dr. Butts knew Appalachian stratigraphy as no one before him, and 
he led me and my colleagues to many places where collections could be made and 
information obtained. I am also grateful to Dr. Butts for the many discussions, 
often heated but always illuminating, on problems of Appalachian stratigraphy. 
Dr. Edwin Kirk, of the U. S. Geological Survey, helped with information on 
sections in Nevada. 
Many friends outside of Washington helped me in the laboratory and field. 
Dr. G. M. Kay furnished information on many localities. Dr. William E. Ham, 
Oklahoma Geological Survey, spent several days in the Arbuckles with me; Dr. 
C. W. Wilson, Vanderbilt University, spent several days in the field and fur- 
nished important information from his wide knowledge of the Central Basin of 
Tennessee. Thanks are due the late Dr. Percy E. Raymond, of Harvard Col- 
lege, for making it possible for me to study the type specimens of Southern 
Appalachian brachiopods described by him and Dr. Bradford Willard. Similar 
acknowledgments are due to Dr. E. M. Kindle and Miss Alice Wilson, both 
former officials of the Canadian Geological Survey. They kindly placed at my 
disposal type specimens of many of Elkanah Billings’ species for study and pho- 
tographing while I was in Ottawa in 1938. Thanks are extended to Dr. W. A. 
Bell, Canadian Geological Survey, for permission to prepare the interior of one 
of the types of the brachiopod Petroria figured on plate 221, E. Dr. C. W. Mer- 
