CHOUTEAU CORALS 



versity of Chicago; G. M. Ehlers, of the 

 University of Michigan; Rousseau H. 

 Flower, of the University of Cincinnati ; 

 and H. E. Vokes, of the American Museum 

 of Natural History. Winifred Goldring, of 

 the New York State Museum, furnished 

 photographs of specimens and data on oc- 

 currence and disposition of specimens. The 

 manuscript has profited through criticisms 

 and suggestions by C. L. Cooper and J. 

 Marvin Weller, of the Illinois State Geo- 

 logical Survey. The writer is grateful to all 

 these people for their cooperation in this 

 study. 



Preparation and Illustration 



Study of internal structure is generally 

 required for accurate identification of cor- 

 als. Formerly thin-sections were made, but 

 this elaborate process is usually unnecessary. 

 Generally a flat-ground surface or a speci- 

 men sawed in parts and smoothed off will 

 furnish all required data. If well calcified 

 material is available, cellulose peel sections 

 can be made. 



Some of the Chouteau corals are illus- 

 trated here for the first time and sections 

 of others are presented for the first time. 

 Previously published sections have varied 

 in enlargement but here most of them are 

 shown at a uniform enlargement unless this 

 would entail an unwarranted waste of 

 space or greater enlargement was desirable 

 to bring out detail. 



The Chouteau corals are variously calca- 

 reous, dolomitic, and silicified, and it has 

 been most convenient to illustrate their in- 

 ternal structure by camera lucida drawings 



or by inked photographs reduced by use of 

 Farmers solution. The two photographic 

 plates show growth habits, general calical 

 features, and minor structural details. 



Primary type specimens of most species 

 have been available for study and they are 

 illustrated either externally or internally 

 or both. If necessary to verify a species, 

 the holotype was sectioned, but otherwise 

 another specimen was used. If possible the 

 calyx was carefully excavated. Thoroughly 

 silicified specimens were etched free with 

 acid. 



Taxonomic Procedure 



Many of the Chouteau species were based 

 upon groups of cotypes, one specimen of 

 which has now been selected as the holotype 

 in each case. Some of these groups included 

 many specimens and some of them were dis- 

 covered to contain specimens belonging to 

 several different genera and species. If the 

 cotypes are not all conspecific a specimen 

 has been chosen as holotype which agrees 

 most closely with the common conception 

 of the species even though it was necessary to 

 disregard the specimen figured or described 

 by the original author. Fortunately, the In- 

 ternational Rules of Zoological Nomencla- 

 ture allow a reviser to make such a selection 

 and thus cause the least amount of confu- 

 sion and do the least damage to existing 

 classification. 



As many as possible of the citations listed 

 in the synonymies were reviewed. Some of 

 the anomalies of stratigraphic distribution 

 have resulted from faulty identifications 

 perpetuated by failure of subsequent work- 

 ers to verify previous work. 



