The Cbondrocraniuiii of an Embryo Pig. 



171 



a broad quadrangubxr plate, limited posteriorly by tbe foramen mag- 

 num, anteriorly by the foramen jugulare or fissura metotica and the 

 auditory bullae, while laterally it passes over into the j^ars lateralis, 

 regio occipitalis. On the boundary between the basal plate and the 



I. par. 



Fig. 1. Sectiou showing the broad basal phite h.p., the iiotochord n.c. near 

 its dorsal surface, and the large auricular branch of the vagus nerve X r.aur. 

 X 10. 



VIII, nervus acusticus ; m.st., stapedial muscle; j.v., jugular vein; l.s.c, 

 lateral semicircular canal ; utr., utriculus ; a.s.c, anterior semicircular canal ; 

 I. par., lamina parietalis ; X, nervus vagus ; XII, nervus hypoglossus. 



pars lateralis the processus par occipitalis arises and extends forward. 

 The basal plate is perforated just median to this process by the 

 foramen nervi hypoglossi (PI. I, /. hyp.). Three branches of the 

 hypoglossus nerve have been demonstrated in a number of mammalian 



