by cross membranous septa into compartments varying from the 

 twentieth to the thirtieth of an inch in diameter. These compart- 

 ments were filled with a transparent gelatinous matter. The columns 

 were so arranged as to form layers, which, on a transverse sec- 

 tion, were seen to have a concentric arrangement, but on a longi- 

 tudinal section, were seen to form hollow cones placed one within 

 the other. This arrangement allowed about three-fourths of the 

 wide extremity of every cone-shaped layer to come in contact with 

 the skin. 



The microscope shewed the walls of the columns and their cross 

 septa to be composed of dense fibrous and filamentous tissue, on 

 which the blood-vessels and nerves were minutely ramified. The 

 gelatinous matter which filled the compartments was seen to be com- 

 posed of very minute cells, the walls of which were composed of a 

 fine transparent membrane, over which the nerves were seen to 

 ramify in the most beautiful manner. The interior of these very 

 minute transparent cells was filled with a transparent jelly. 



A rough chemical examination shewed the oi-gan to be composed 

 principally of gelatine, and in small part of albumen. No fibrin was 

 observed in it. 



The organ was supplied with nerves from three sources, viz., from 

 the lateral branch of the eighth pair, and from the anterior and pos- 

 terior caudo-spinal nerves. 



This organ did not exist in equal development in every species 

 of Ray. In most of them it was merely rudimentary, not Ijeing 

 thicker than a crow-quill or common pen, and consisted of only four 

 or five columns, similarly divided into cells by cross membranous 

 septa. 



The author formed the conclusion that this was an electrical ap- 

 pai'atus from the following purely anatomical considerations, as he 

 had not an opportunity of ascertaining the occurrence of electrical 

 discharges from the organ by an examination of living specimens. 



1. The structure of the organ was the same as that of the 

 electrical apparatus of the Torpedo and Electrical Eel — consisting of 

 membranous tubes or columns arranged in layers, each column being 

 divided into distinct compartments filled with a gelatinous fluid. 



2. All the layers of tubes communicated with the skin, and that 

 skin was abundantly supplied with mucus. 



3. The organ was supplied not only with spinal nerves, but with 

 the descending branch of the eighth pair, which, along with a branch 

 of the fifth pair, is the electrical nerve of the allied genus Torpedo ; 



