CONTENTS. 



Page. 



Letter of transmittal 9 



Preface 11 



Cliapter I. Geologic development and geographic distribution of American 



fossil Brachiopoda 13 



Geologic development 13 



Geographic distribution , 17 



Table I Brachiopodgenera alphabetically arranged, their geologic dis- 

 tribution, and North American specific representation 18 



Table II. North American Paleozoic representation of the orders, super- 

 families, and families, geologically arranged 25 



Tables of North and South American species, geologically arranged 26 



Table III. Cambrian Brachioi^oda 26 



Table IV. Ordovician Brachiopoda '29 



Table V. Silurian Brachiopoda 36 



Table VI. Devonian Brachiopoda 43 



Table VII. Carboniferous and Permian Brachiopoda 57 



Table VIII. Mesozoic Brachiopoda 67 



Table IX. Cenozoic and recent Brachioijoda 68 



Table X. South American fossil Brachiopoda (;9 



Chai^ter II. Brachiopod termiuologj^, applied to fossil forms 73 



Chai)ter III. Biologic development of the Brachiopoda 78 



Ordinal development 78 



Atremata 78 



Neotremata 7'J 



Protremata 81 



Telotremata 8.") 



General development 88 



Structural characters 90 



The protegulum 90 



The prodeltidium 91 



Significance of the prodeltidium 93 



Development of cardinal areas and articulation 97 



Development and significance of the deltidium 98 



Thechilidium 99 



Origin and function of the spondylium 09 



Crura and cruralium 102 



Morphologic equivalents 102 



Summary 102 



Chapter IV. Morphology of the brachia, by Charles E. Beeeher 105 



Classification of brachial structures 106 



Leiolojjhus stage 107 



Taxolophus stage 107 



Trocholophus stage 107 



Schizolophus stage 108 



5 



