xii CONTENTS 



PAGE 



III. STUDIES IN THE DEVELOPMENT OF THE BRACH- 

 IOPODA 



1. DEVELOPMENT OF THE BRACHIOPODA 229 



I. Introduction 229 



The Protegulum 230 



Affinities . 232 



Modifications from Acceleration 233 



Differences in the Valves 234 



Genesis of Form 238 



Types of Pedicle-openings . 240 



Atremata 243 



Neotremata . 244 



Protremata 244 



Telotremata 245 



II. Classification of the Stages of Growth and Decline . 246 



Embryonic Stages 247 



Larval Stages 250 



Origin of the Deltidium and Deltidial Plates . . 257 



Post-embryonic Stages 265 



Nepionic Period 267 



Neanic Period 268 



Ephebic Period 269 



Gerontic Period 269 



Synopsis 271 



References 272 



III. Morphology of the Brachia 274 



Classification of Brachial Structures .... 276 



Leiolophus Stage 277 



Taxolophus Stage 277 



Trocholophus Stage 278 



Schizolophus Stage 278 



Ptycholophus Stage 280 



Zugolophus and Plectolophus Stages . . . 281 



Spirolophus Stage 282 



References 285 



2. SOME CORRELATIONS OF ONTOGENY AND PHYLOGENY 



IN THE BRACHIOPODA 286 



3. REVISION OF THE FAMILIES OF LOOP-BEARING BRACH- 



IOPODA 290 



The Terebratulidae 290 



The Terebratellidae 291 



Magellaniinae 293 



Dallininae 295 



Comparisons and Homologies 299 



Morphogeny from Gwynia to Megathyris 302 



