THE PRIMORDIAL CRANIUM OF THE CAT 



ROBERT J. TERRY 



Department of Anatomy, Washington University Medical School 



THIRTY FIGURES (tWELVE PLATEs) 



CONTENTS 



Introduction 282 



Material and methods 285 



Part I. Observations 287 



Basal plate. Embryos of 23.1 mm 287 



Occipital region 289 



Atlas and epistropheus 293 



Basal plate and occipital region in smaller embryos 294 



Otic region. Embryos of 23.1 mm 298 



Pars canalicularis. Outer form 299 



Pars cochlearis 302 



Cavities of the otic capsule ■ 305 



Otic region of smaller embryos. 311 



Nerves in the otic region 314 



Blood vessels in the otic region. . ; '. 316 



Orbito-temporal region in embryos of 23.1 mm 317 



Orbito-temporal region in smaller embryos 325 



Ethmoidal region in embryos of 23.1 mm 329 



Ethmoidal region of smaller embryos 340 



Part II. Discussion 342 



Occipital region 342 



Basal plate ■ 342 



Atlas 351 



Occipito-atlantal articulation 353 



Plane of the foramen magnum 354 



Basal fissures 355 



Foramen magnum 356 



Otic region 357 



Position of the otic capsules 357 



Origin of the cartilaginous otic capsule 359 



Foramina acustica and meatus acusticus internus : 363 



Foramen perilymphaticum 364 



Cavum vestibulare 365 



Lamina parietalis and tectum posterius 366 



Facial and acustic nerves 369 



281 



JOURNAL OF .MORPHOLOGY, VOL. 29, NO. 2 

 SEPTEMBER, 1917 



