Turner, Morphology of the Avian Brain. 55 



emerging, become the optic nerve. This is a very large 

 nerve. 



Thirds or ocnio-motor (Plate V, Figs. 9, 13). — This is a 

 small nerve. It arises from the diencephalon near to and 

 laterad to the infundibulum and immediately cephalad to 

 the metencephalon. 



Fourth^ or pathetic (Plate V, Figs. 9, 13). — This is a 

 small nerve. At a short distance caudad of the cephalic 

 extremity of the metencephalon, the fourth nerve emerges 

 from between the mesencephalon and the metencephalon. 



Fifth, or trigeminal (Plate V, Figs. 4, 7, 9, 13). — This 

 is a large nerve. It arises from the side of the metenceph- 

 alon, about half way between its dorsal and ventral surfaces 

 and a short distance caudad to the optic lobes. 



Sixth, or abducens (Plate V, Figs. 7,9, 13). — At a short 

 distance caudad to the trigeminal nerve and about half way 

 between the meson and the lateral border, the small sixth 

 nerve leaves the metencephalon. 



Seventh and eighth, or facial and auditory (Plate V, 

 Figs. 9, 13). — A short distance caudad to the trigeminal 

 nerve and near the dorsal surface of the metencephalon, 

 there is a large nerve root. This is the common root of the 

 seventh and eighth nerves. 



Ninth aiid tenth, or glossopharyngeal and p7ieumogastric 

 (Plate V, Figs. 1,4, 9, 13). — Caudad and slightly ventrad 

 to the seventh and eighth nerve root, the medium-sized root 

 of the ninth and tenth nerves arises from the metencephalon. 



Eleventh, or spinal accessory (Plate V, Fig. 4). — The 

 eleventh nerve arises, as a number o# small strands, from the 

 lateral surface of the metencephalon. Cephalad, this nerve 

 unites with the common root of the ninth and tenth nerves; 

 caudad, it passes beyond the root of the first cervical nerve. 



Twelfth, or hvpogiossal. — This is a small nerve, which 

 arises from the metencephalon at about the same distance 

 from the meson as the sixth nerve and immediately cephalad 

 to the caudal extremity of the metencephalon. 



