174 MAMMALIA. 



of the chest, and that of the left side forms a junction with the prolongation, but 

 becomes again separate before it passes through the diaphragm ; in the hedgehog, 

 the splanchnic nerve extends over the heads of the four last ribs ; it receives fresh 

 branches from the sympathetic as it descends to the semilunar ganglion, thus forming 

 a plexus on the sides of the vertebrae, in some measure similar to that in the baboon. 

 In the monkey, the splanchnic nerve separates from the prolongation lower down than 

 in the hedgehog, just below the last rib. In the jaguar, the splanchnic nerve leaves 

 the prolongation a little above the diaphragm, and passes to the semilunar ganglion. 

 In the pig, the prolongation, just at its passage through the diaphragm, sends off the 

 splanchnic nerve and forms a ganglion, from which a branch is sent to the last dorsal 

 nerve. These variations of arrangement do not seem to make any difference, either 

 in the formation of the semilunar ganglia or the branches proceeding from them. In 

 the baboon, there is a distinct communication between the right phrenic nerve and 

 semilunar ganglion. In the porpoise, the thoracic ganglia are well developed, and, 

 on the whole, larger than in mammalia; they send branches inwardly towards the 

 aorta and to form the splanchnic nerves, and outwardly to the vascular rete, besides 

 others to the spinal intercostal nerves : the ganglia of the lower thoracic portion are 

 smaller than the upper ; towards the lower part of the thorax the prolongation passes 

 behind the psoas muscle. 



The renal capsules and semilunar ganglia are of various shapes in different 

 animals, and in the two sides of the same ; there is frequently an intimate union 

 between these and the splanchnic nerves, sometimes by fleshy ganglion, sometimes by 

 a fibrous membrane or filaments ; but it is not the same always in each species. In 

 simias, each semilunar ganglion is composed of a dense membrane and some fleshy 

 parts, but the fleshy parts are not near so large as they generally are in man ; in the 

 jaguar, a considerable portion is fleshy, and the rest a dense membrane ; it is nearly 

 the same in the dog and fox ; in the ass, a small portion is fleshy and the rest mem- 

 branous, but the fleshy part is not of so dense a texture as in man ; in a full-grown sow, 

 it is formed of a very delicate membrane, with some small patches of fleshy ganglion 

 amongst it, which are much less than in the ass ; in the hedgehog, it is membranous 



