TOL. LXni.] FHILOSOPHICAL TRANSACTIONS. 47p 



limits they occupy the whole space between the skin of the upper and of the 

 under surfaces : they are thickest at the edges near the centre of the fish, and 

 become gradually thinner towards the extremities. Each electric organ, at its 

 inner longitudinal edge, is unequally hollowed ; being exactly fitted to the 

 irregular projections of the cranium and gills. The outer longitudinal edge is a 

 convex elliptic curve. The anterior extremity of each organ, makes the section 

 of a small circle ; and the posterior extremity makes nearly a right angle with the 

 inner edge. Each organ is attached to the surrounding parts by a close cellular 

 membrane, and also by short and strong tendinous fibres, which pass directly 

 across, from its outer edge, to the semicircular cartilages. 



They are covered, above and below, by the commoti skin of the animal; 

 under which there is a thin fascia spread over the whole organ. This is com- 

 posed of fibres, which run longitudinally, or in the direction of the body of the 

 animal : these fibres appear to be perforated in innumerable places ; which gives 

 the fascia the appearance of being fasciculated; its edges all around, are closely 

 connected to the skin, and at last appear to be lost, or to degenerate into the 

 common cellular membrane of the skin. Immediately under this, is another 

 membrane, exactly of the same kind, the fibres of which in some measure 

 decussate those of the former, passing from the middle line of the body outwards 

 and backwards. The inner edge of this is lost with the first described; the 

 anterior, outer, and posterior edges, are partly attached to the semicircular car- 

 tilages, and partly lost in the common cellular membrane. 



This inner fascia appears to be continued into the electric organ, by so many 

 processes, and thereby makes the membranous sides or sheaths of the columns 

 which are presently to be described ; and between these processes the fascia 

 covers the end of each column, making the outermost or first partition. Each 

 organ, of the fish under consideration, is about 5 inches in length, and at the 

 anterior end 3 in breadth, though it is but little more than half as broad at the 

 posterior extremity. Each consists wholly of perpendicular columns, reaching 

 from the upper to the under surface of the body, and varying in their lengths, 

 according to the thickness of the parts of the body where they are placed ; the 

 longest column being about an inch and a half, the shortest about ^ of an inch 

 in length, and their diameters about ^Sg. of an inch. 



The figures of the columns are very irregular, varying according to situation 

 and other circumstances. The greatest number of them are either irregular 

 hexagons, or irregular pentagons ; but from the irregularity of some of them, 

 it happens that a pretty regular quadrangular column is sometimes formed. 

 Those of the exterior row are either quadrangular or hexagonal ; having one side 

 external, 1 lateral, and either 1 or 2 internal. In the 2d row they are mostly 

 pentagons. Their coats are very thin, and seem transparent, closely connected 

 with each other, having a kind of loose network of tendinous fibres, passing 



