Chap. 27.] Brain of Birds. 275 



medulla fpinalis. In this pare of it feveral appearances 

 are to be noticed. We obferve four eminences,, two 

 named the corpora olivaria, and the other two the cor- 

 pora pyramidalia. Immediately behind thefe we dif- 

 cover the beginning of two grooves, one above and 

 one below. Thefe becoming deeper divide the me- 

 dulla oblongata into two cylinders. When we fepa- 

 rate thefe with the fingers we obferve feveral medullary 

 cords which crofs each other in palling from one lateral 

 portion to the other. 



The corpora olivaria and pyramidalia are whitifli 

 eminences (ituated longitudinally near each other im- 

 mediately behind the pons Varolii. The corpora oli- 

 varia are outermoft and are nearly of an oval (hape. 

 Between them are the corpora pyramidalia, each of 

 which terminates in a point. 



It is obfervable, in general, with refpect to the emi- 

 nences of the medulla oblongata, that thofe which are 

 medullary wit'iout are, chiefly cortical within. What 

 are the diftinct functions of thefe fubftances which ap- 

 pear fo different to the eye, and what purpofes are an- 

 fwered by their intermixture, are points which mud 

 remain undetermined till we can diicover the connection 

 between the mind and the body, and enter into the 

 fecret mechanifm of this wonderful engine of fenfatioa 

 and intellect. 



The brain of birds is covered with the common 

 membranes,- but its external furface is not formed into 

 fo many gyrae or convolutions as ours. Its anterior 

 part is quite folid, of a cineritious colour, and fo far 

 has a refemblance of the corpora ftriata as to give rife 

 to the olfactory nerves. The whole of it appears to 

 us imperfect, and we can fcarcely diftinguifti whether 

 there is any thing analogous to a third or fourth ven- 

 tricle ; neither the corpus callofum^ fornix^ nates nor teftes> 

 T 2 c*i 



