CHANGES DURING GROWTH IN THE SKULL 



OF THE RODENT OTOSPERMOPHILUS 



GRAMMURUS BEECHEYI 



BY 



E. RAYMOND HALL 



CONTENTS 



PAGE 



Introduction 356 



Acknowledgments 356 



Materials 357 



Individual skull elements 358 



Nasals 358 



Premaxillae 358 



Maxillae ■. 359 



Lacrymals 360 



Frontals 361 



Parietals 367 



Squamosals 370 



Jugals 371 



Orbitosphenoids 371 



Alisphenoids 372 



Palatines : ^ 373 



Pterygoids 374 



Vomer and ethmoids 375 



Presphenoid 376 



Basisphenoid 377 



Basioccipital 377 



Exoccipitals 378 



Supraoccipital 379 



Interparietal 379 



Tympanies 381 



Petrosals 384 



Auditory ossicles 385 



Mandible 386 



Teeth 390 



Cranium as a whole 391 



In review 400 



Study of a large series 401 



Literature cited 404 



