18 PISCES. 



nerve, and, after communicating with the par vagum, it terminates in the intestines and 

 other viscera. The prolongation is then continued down on each side of the aorta to 

 the tail, giving filaments to the arterial branches and spinal nerves, and near the anus 

 sending off filaments which unite and accompany the spermatic artery to the ovaries. 

 In the skate the sympathetic is different ; its consistence is softer ; it forms a large 

 ganglion, the branches of which may be traced to accompany the mesenteric arteries to 

 the viscera. Some filaments also are distributed about the testes, and others pass 

 towards the aorta; but these were very soft, and not satisfactorily traced to their 

 precise terminations. 



In fishes, in addition to the sensitive, voluntary, and involuntary divisions of the 

 nervous system, there is also a sympathetic nerve. The parts of the brain concerned 

 in the special and common sensitive functions occupy a very large share ; a very small 

 portion of it, therefore, remains for forming voluntary centres ; but such agree with 

 the simple voluntary impulses required for animals having such a medium to move in, 

 and whose skeleton allows only simple motions. The involuntary portion gives origin 

 to the glosso-pharyngeal and par vagum which supply principally the branchiae and 

 stomach, but the par vagum sends large branches on the sides for favouring respiratory 

 functions when the branchiae are not sufficient. In some instances ganglia are not 

 attached to the spinal nerves, and in others are very small, and therefore cannot give 

 the respiratory properties to the skin. 



From the higher condition of all the organs of the senses, the intellect must 

 receive more vivid external impressions ; but whether it has higher intrinsic powers 

 on account of the larger brain than some of the invertebrate is very doubtful. Fishes 

 inhabit water in every part of the globe, and are required to subsist on various sorts 

 of nourishment ; and as they must therefore have different capacities, they must have 

 corresponding variations in the structure of their bodies. The appetite for food 

 appears to be their predominant desire, and providing for its gratification to form 

 their chief occupation ; and as this, in many instances, is very voracious, they must 

 be constituted not only with a peculiar digestive apparatus, but with subtlety for 

 taking their prey, and strength for pursuing it, as well as for defending themselves 



