ANIMAL ELECTRICITY AND PHOSPHORESCENCE. 83 



investing the electrical organs. The outer one has longitudinal fibres, which 

 are rather loosely adherent, and around the margin of the organs seem to 

 inosculate with the skin. The inner fascia is of considerable density, forms 

 the immediate tunic of the electric columns, and sends delicate processes, 

 with an accompanying network of arteries, veins, and nerves, down between 

 them to form their partitions. Throughout their whole extent the essential' 

 part of the electrical organs is formed by a whitish soft pulp, divided into 

 numerous pentagonal prisms by the fascial processes above mentioned. 

 These lie closely together, parallel with one another, and perpendicularly 

 between the dorsal and ventral surfaces of the fish, so that their extremities 

 are separated from these surfaces only by their fascia and the common in- 

 teguments. When these are removed, the columns present something of the 

 appearance of a honeycomb. The columns are longest next to the head and 

 gills, and, being at these points about one inch in length, thence gradually 

 diminish outwardly, until on the external margin they are only about one- 

 sixth of the length of the internal ones. Most of these columns are either 

 irregular pentagons or irregular hexagons; a few are nearly tetragonal. 

 They are united to one another by short but strong fibres, and by a reticular 

 expansion of tendinous threads spread over them. Their number varies 

 considerably according to the age of the fish, but averages about 470 to 

 each organ. (Coldstream.) 



The nerves distributed to the electrical organs are of great size. They 

 consist of three principal trunks arising from the cerebro-spinal system. 

 The two anterior are portions of the fifth pair ; the third is a branch of the 

 tenth. They appear to arise in part from an appendage to the cerebellum 

 ('fourth encephalic lobe'), and terminate upon the sides of the columns by 

 loops. 



Rudimentary conditions of an electrical apparatus are met with in other 

 rays, as for example Raia batis (skate) and Raia clavata. Each of these 

 possess an electrical organ imbedded in the muscles of the tail. It com- 

 mences on either side of the caudal region, at about one-third of its length 

 from the base, and, extending toward the tip, gradually occupies much of its 

 space. Its form is that of a tube surrounded by a nervous covering. It is 

 supplied by spinal nerves, which resemble in their distribution those of other 

 electrical organs. (Murray.) The electricity elicited from this apparatus is 

 similar to though weaker than that from the Torpedo. (Robin.) 



Gymnotus electricus (electrical eel). Body long, eel-like, naked, without 

 dorsal fin, covered with mucoid secretion. Head is short, somewhat flat- 

 tened from above downward, and furnished with a number of mucous folli- 

 cles. Mouth large, lips thick and mobile. Upper jaw a little longer than 

 lower, and furnished with a number of small acute teeth. The tongue is 

 large and furnished, together with the pharynx, with a number of small 

 papillae. The eyes, which are situated upon the superior aspect of head, are 

 very small, and each possess a yellowish iris. 



