AVES. 85 



much with one as the other. Branches from the first thoracic ganglion communicate 

 with the pulmonary branches of the par vagum, and accompany the large blood-vessels 

 to the heart. The first large splanchnic nerve proceeds from the thoracic portion, and 

 after communicating with that of the right side on the coeliac artery, the branches 

 proceed from the union along the branches of this artery to the liver, the upper portion 

 of the small intestines and the gizzard, and on this organ communications take place 

 with branches of the par vagum. The second large splanchnic nerve is formed by 

 branches from the prolongation, and several thoracic ganglia; it corresponds more 

 particularly with the splanchnic nerve of mammalia ; it passes to the renal capsule, 

 with which it becomes intimately united, and then distributes its branches to the small 

 intestines and the ovaries or testes. After the second large splanchnic nerve has been 

 given off, the sympathetic passes downwards and communicates with the spinal 

 nerves ; it sends some branches upwards to communicate with others from the 

 splanchnic nerves, and give branches to the kidney, and several to the mesocolon, many 

 of which advance forward, and form an arch near to that of the mesocolic artery, 

 which at the superior part communicates with the splanchnic nerve, and gives branches 

 to the intestines, and others to the delicate peritoneum. The sympathetic then com- 

 municates freely with the anterior trunks of most of the spinal nerves within the 

 pelvis ; those below the nerves given to the inferior extremity form several large 

 nerves, which pass downwards to the muscles and other parts connected with the 

 cloaca and skin. The preceding description will apply generally to this class, if an 

 allowance be made for a difference in the number of the vertebrae and the size of the 

 parts to be supplied with nerves. 



The brain of birds differs from that of many of the amphibia in the form, and 

 comparatively large size of the hemispheres. In the greater dimensions of the 

 anterior lobes, in proportion to the olfactory nerves ; in the very thin parietes of the 

 posterior part of the lateral ventricles ; in the shape and magnitude of the striated 

 bodies ; in the larger size, and different situation, of the optic thalami ; in the flattened 

 summit, but greater circumference of the optic lobes, and in the shape of the cavity, 

 which corresponds with their external form. In the external shape and appearance 



