PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 3 
that produced so many of the small and unusual fossils such as those from Pratt 
Ferry, Porterfield Quarry, and Friendsville. 
Gifts to the Museum.—I am grateful to many of my colleagues for gifts of 
important material : 
Dr. G. M. Kay, Columbia University, presented specimens from Ontario and 
New York; Dr. B. N. Cooper presented a fairly large collection from the Appa- 
lachian Valley in Virginia; Dr. C. E. Decker presented to Dr. Ulrich an exten- 
sive suite of collections from the Arbuckle Mountains; O. C. Cole, of Kenyon, 
Minn., gave the Museum many brachiopods from the Ion and Prosser forma- 
tions of Minnesota; Dr. G. Winston Sinclair presented several collections, one 
from Paquette Rapids, Ontario, another from the vicinity of Montreal, and an 
interesting lot of Strophomenas from Quebec and Ontario; Dr. Robert R. Shrock 
presented an extensive suite of specimens from the cryptovolcanic structure in 
Kentland, Ind. ; Dr. Helgi Johnson, of Rutgers University, and Dr. Cecil Kindle, 
of City College of New York, gave small but choice collections of Table Head 
material from Newfoundland; Dr. C. W. Merriam presented the Museum with 
an extensive collection of early Middle Ordovician fossils from the Antelope 
Valley of Nevada; Dr. Lawrence D. Whitcomb presented specimens of the new 
genus Limbimurina from Pennsylvania; Dr. L. F. Hintze presented a few speci- 
mens from the Confusion Range, Utah; Ray C. Gilbert made a present of a few 
exceptional specimens from the lower part of the section near Lusters Gate, 
Blacksburg, Va.; Dr. Robert B. Neuman presented a collection from the Row 
Park and New Market formations in Maryland and Pennsylvania; a superb lot 
of fossils from the Arbuckles sequence was donated by Dr. A. R. Loeblich, Jr., 
now of the U. S. National Museum staff. 
Borrowed material_—Early in the work on this monograph the officials of the 
Carnegie Museum lent the large and valuable collection of Chazy brachiopods 
accumulated by the late Dr. P. E. Raymond, who made pioneer studies on this 
group of rocks and its brachiopods. Peabody Museum, through Dr. C. O. Dun- 
bar, lent material from the Mingan Islands. Dr. G. M. Kay, Columbia University, 
lent a few rare specimens from New York and Ontario. 
PREPARING THE FOSSILS 
The collection on which this monograph is based consists of many superb 
specimens. The material was prepared by several methods. Throughout the 
United States and Canada fossils frequently occur in a silicified state. In the 
Appalachians, many localities exist where the fossils can be removed from the 
rock by means of hydrochloric and acetic acids. Indeed, in some localities such 
as the Cahaba Valley, Ala., and the region around Friendsville, Tenn., fossils 
abound in the residual soil resulting from the deep weathering of the Little Oak 
and Arline limestone. In these places the silicification is often somewhat coarse 
in texture but is, nevertheless, very good. 
Muddy limestones frequently yield good silicified specimens. In etching such 
material, great patience is required because decalcification of the rock yields a 
mass of mud, often fairly hard, from which the fossils must be taken. It requires 
