290 ACCOUNT OF A RIBBON FISH 
of a double-edged sword blade, being excessively compressed ; 
its greatest thickness is decidedly nearer the ventral than the 
dorsal border ; from the thickest part it slopes gradually to each 
border, the dorsal being the sharper. The length of the fish is 
12 ft. 3 in., the mouth not being projected forward ; immediately 
behind the gills it measures 83 in. in depth ; from this point it 
gradually enlarges to a distance of upwards of two feet further 
back, where it attains its greatest depth of 111 in. ; this dimen- 
sion remains much the same for 13 ft. beyond ; it then gradually 
but perceptibly diminishes to the end of the dorsal fin, where 
the depth is 3 in. 
The thickness through the head at the gill-covers is 2 in., at 
the part of greatest depth 22 in. ; Plate I. fig. 2 shows a section 
at this part. Opposite the anus somewhat less ; it then gradually 
diminishes to the end of the dorsal fin, where it is upwards of 
three-eighths of an inch, fig. 3. 
The fishermen state that when this fish was first taken it was 
all over of a brilliant silvery iridescent hue, resembling in inten- 
sity that of the fresh herring, which soon faded, and shortly after 
we saw it, all traces of the iridescence except those already men- 
tioned had disappeared. The skin is covered over with a silvery 
matter in which no scales are visible to the naked eye, but 
which is most readily detached from the skin and adheres to 
anything it comes in contact with. Submitted to the microscope 
it is found to consist partly of minute convex scale-like bodies of 
elongated pyramidal outline with the base rounded, Pl. I., fig. 4, 
which are formed of fine clear crystalline-looking filaments, ar« 
ranged side by side, and radiating from the apex to the base of 
the scale; these filaments grow much finer towards the base, 
where a number of minute granules are also observed. The 
scales remind one of some of those seen on the wings of moths. 
The bulk of the silvery matter of the skin, however, is made up 
of a soft matter finely granular, and presenting numerous trans- 
parent fragments of what have the aspect of acicular crystalline 
bodies. We have not been able to detect the mode of arrange- 
ment of the scale-like bodies on the skin. Round the posterior 
margin of the preoperculum is a broadish dusky mark on the 
