THE CHONDROCKANIUM OF AN EMBRYO PIG, 

 SUS SCROFA. 



a contkibution to the mokphology of the 

 Mammalian Skull. 



CHARLES SEARING MEAD. 



With 11 Text Figures and 4 Plates. 



CONTENTS. 



PAGE 



Introduction 167 



The Skull as a Whole 169 



Planum Basale 170 



Regio Occipitalis 175 



Regio Otica 178 



Auditory Capsules ISO 



Sound-Conducting Apparatus 185 



Nerve Foramina in the Region of the Ear-Capsules 188 



Regio Orbitotemporal is 192 



Regio Ethmoidalis 199 



Conclusions . 206 



Bibliography 208 



Introduction. 

 The study of the chondrocranium of Sus is of value not only in 

 assisting us to understand the structure of the adult skull in this 

 form, but also on account of its bearing on the general morphology 

 of the mammalian cranium. Owing to the generalized dentition 

 and the structure of the feet, Sus has been placed relatively low in 

 the ungulate series. Hence, we would expect many primitive char- 

 acters to be retained in its cartilaginous cranium, and, indeed, this 

 is the fact, for a number of reptilian characters are present. This 

 chondrocranium is also valuable for comparison with those of pri- 

 mates and insectivores. 

 The American Journal of Anatomy. — Vol. IX, No. 2. 



