CONTENTS 



Page 



Introduction * 



Division of work •^ 



Location of specimens ^ 



Technique "^ 



Species lists 



Genetic lines 



Acknowledgments 



Part I. Brief definitions of brachiopod terms " 



Part II. Principles of morphogenesis or evolution of form 12 



12 

 Need of taxonomy 



12 

 Rise of brachiopod genera 



13 

 The genus concept 



Paleoecology 



Homoeomorphy 



Part III. Morphology of the orthoid shell 18 



Morphology of the exterior 18 



Orientation of the shell 18 



Commissures '" 



Convexity ' 



Interareas ^^ 



Deltidium •■■ 21 



Modifications of the delthyrium (deltidium) 21 



Function of the deltidium 22 



Lateral plates 



Modifications of the notothyrium (chilidium and chilidial plates) 23 



Morphology of the ventral interior 



Articulation 



Teeth Ys 



Sockets -P 



Dental plates 



Spondylium ^, 



History of the term 



Present views and definitions 



«j , 29 



Septa 



.; , 30 



Musculature 



32 

 Paliial and genital markings -- 



Pallial markings ^^ 



» Genital or ovarian markings 



