NEUROLOGY OF THE SiUROrSIDA. 



259 



Py- 



flQ, 90. — A, C, the brain of a Lizard (_P6a'm7n08avrus BwiffalenMsX and B, D, of n liinl 

 {MeleagHs giilloxiaro^ the Turkey), drawn a3 if tliey were of equal lengths. A, B, 

 viewed from above ; 0, D, from the left side. (9?/'., Olfactory lobes ; Prt., Pineal er'aiJiI ; 

 //m/>., cerebral hemispheres; .J/&., optic lobes of the mid-brain; (76., cerebellum ; M, 

 O^ medulb oblont^ata ; ii.^ in., m., second, fourth, and sixth pans of cerebral nerves ; 

 Py., pituitary body. 



base of the brain, and are connected over the aqumductiis 

 Sylvii by a broad commissural band. 



Each prosencephalic lobe contains a lateral ventricle (con- 

 tinuous through the foramen of Munro with the third ven- 

 tricle), which is little more than a fissure between the very 

 thin inner wall of the lobe and its thick outer part, which con- 

 tains the corpus striatum. The corpora striata are united by 

 an anterior commissure, which is not of large size. The thin- 

 ning of the inner wall of the lobes, from the margin of the 

 foramen of Munro backward, wliich gives rise to the fissure 

 of Bichat in the Mammalia, extends for a very short distance 

 in the Sauropsida, even in birds. 



The olfactory lobes are usually elongated, and contain ventri- 

 cles continuous with those of the prosencephalic hemispheres. 



In all Sauropsida the motor nerves of the tongue pass 

 through a foramen in the exoccipital bone. Hence, twelve 

 pairs of cranial nerves are present, except in the Ophidia, 

 which possess no spinal accessory nerve. 



The lateral cutaneous branches so generally sent to the 



■ trunk by the pneumogastric in the Ichthyopsida are absent, 



but the pneumogastric gives a recurrent branch to the larynx. 



The third, fourth, and sixth nerves arise quite independently 



of the fifth. 



