C N T E N T S 



Letter of transmit t;il 9 



Pielaoe 11 



Chapter I. (ieologic development and i;e()grai)bie (listiihntion of Auieriean 



fossil Braeliiopoda 11^ 



Geologic development 13 



GeoiiTapliie distribution 17 



Table I Braehiopodgeuera alphabetically arranged, their ge()l<>gi(; 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 Braeliiopoda 26 



Table IV. Ordovician Brachiopoda 29 



Table V. Silurian Brachiopoda 36 



Table Vl. Devonian Brachiopoda — 43 



Table VII. Carbouilerons and I'ermian Braeliiopoda 57 



Table VIII. Mesozoie Brachiopoda 67 



Table IX. Ceuozoic and recent Br!icliioi)oda 68 



Table X. South American iossil Brachiopoda (i9 



Chapter II. Brachiopod terminology, applied to fossil forms 73 



Chapter III. Biologic development of the Brachiopoda ■. 78 



Ordinal development 78 



Atremata 78 



Neotremata ~'j 



Protremata 81 



Telotremata 85 



General develoi>ment 8S 



Structural characters 00 



The protegul nm [)() 



The prodcltidium !)1 



Significance of the prodeltidium 93 



Development of cardinal areas and articulation 'M 



Development and signilicnnce of the dcltidiiim 98 



Thechilidinm 99 



Origin and function of the spondylium 99 



Crura and cruralinm 102 



Morphologic ef|uivalents 102 



Summary 1 02 



Chapter IV. Morphology of the brachia, by Charles K. Beecher 105 



Classification of brachial structures 106 



Leiolophus stage 107 



Taxolophus stage 107 



Trocholophusstage 107 



Schizolojihus stage 108 



