PARTS IX THE IXTERPEDUXCULAR SPACE. 537 



situated between the peduncles, the bottom of which is composed of greyish 

 matter, connecting the diverging crura together, and named pons Tarini. 

 It is perforated by numerous small openings for the passage of blood-vessels ; 

 and some horizontal white striae usually pass out of the grey matter and turn 

 round the peduncles immediately above the pons. 



Fig. 367. 



Fig. 367. BASE OP THE BRAIN WITH THE ORIGINS OP THE CEREBRAL NERVES. ^ 



This figure is taken from an adult male brain which had been hardened in alcohol. 



1, superior longitudinal fissure ; 2, fissure of the olfactory tract and lower part of the 

 superior convolution ; 2', orbital convolutions; 2", external or inferior frontal convolu- 

 tion ; 3, inner part of the fissure of Sylvius, near the anterior perforated spot ; 3, 3, outer 

 part; 4, inner convolution of the temporal lobe; 4', middle convolution; 4", outer con- 

 volution; 5, 5', occipital lobe; 6, on the right pyramidal body of the medulla oblongata 

 above the decussation ; 7, amygdaloid lobe of the cerebellum ; 8, biventral lobe ; 9, 

 lobulus gracilis ; 10, posterior inferior lobe ; +, the inferior vermiform process; I, 

 olfactory bulb ; I', the tract divided on the left side, showing the three white striai by 

 which it is connected with the brain ; II, in the anterior perforated spot, marks the right 

 optic nerve; the left has been cut short; III, on. the right crus cerebri, denotes the third 

 pair ; IV, on the inner convolution of the middle lobe, the fourth pair ; V, the trige- 

 minus; VI, on the pons Varolii, the sixth ; VII, also on the pons Varolii, the seventh ; 

 VIII, on the left lobe of the cerebellum below the horizontal fissure and the flocculus, 

 denotes the eighth pair; IX, on the upper part of the right amygdaloid lobe, denotes 

 the ninth pair ; X, on the same, the suboccipital nerve. 



The corpora albicantia or mammillaria are two round white eminences in 

 front of this fossa, each about the size of a small pea, surrounded by grey 

 matter, and connected together across the middle line. 



The corpora albicantia are formed, as will hereafter be explained, by the anterior 

 extremities of the fornix ; hence they have also been named bulbs of thefornix. In 



