134 The Alligator and Its Allies 



caudad to the acoustic and extending along the 

 upper border of the medulla and beginning of the 

 spinal cord, are seen a dozen or more small nerve 

 roots, which unite to form the glossopharyngeal, IX, 

 vagus, X, and spinal accessory, XI, nerves. Ven- 

 tral to the roots of the last, on the ventral surface 

 of the medulla, arise the roots of the hypoglossal 

 nerve, XII. A short distance caudad to this nerve 

 are seen the first two spinal nerves, I and 2, which 

 have, as noted above, no dorsal roots. 



A ventral view of the brain is shown in Figure 30, 

 B. The cerebral hemispheres, VH, have the same 

 outline, of course, as in the dorsal view, but the 

 rounded projection from the caudal end of each 

 is here seen on each side of the infundibulum, Inf. 

 The infundibulum is in close contact with the 

 chiasma anteriorly, and lies close between the 

 converging optic tracts, Tr. opt. From the chi- 

 asma the optic nerves, II, extend, in an antero- 

 lateral direction, almost at right angles to each 

 other. The appearance of the olfactory tracts, I, 

 is the same as in the dorsal view. Caudad to the 

 infundibulum, from the cerebral peduncles, ZH, 

 arise the rather small oculomotor nerves, III. 

 Caudad to these, from near the ventral fissure, 

 on the middle region of the medulla, arise the ab- 

 ducens nerves, VI, and from the ventral side of the 

 posterior part of the medulla and of the anterior 

 end of the cord arise the hypoglossal, XII, and 

 the first two spinal nerves, i and 2. The ori- 



