56  Ayres's Description of a New Genus of Fishes. 
is nothing in any other species known, with which we may 
compare it. We have, it is true, an indication of something 
. like it on the figure of Stomias boa, given by Valenciennes, 
but as no mention is made of it in the description, I am led 
to believe that the light spot is simply an accidental occur- 
rence in the engraving. We are, however, not left to anal- 
ogy, the microscope decides the point at once. ‘This anoma- 
lous body is composed of muscular fibres! -For this strange 
discovery I am indebted to Prof. Agassiz. With a power of 
four hundred, the fibrous structure is too plain to be mistaken, 
though when magnified only two hundred diameters this 
structure is not visible. I am also assured by him that no 
such body exists on the cheek of Stomias. But though we 
are thus made certain of the nature of this organ, we are 
nearly as far as ever from a full understanding of its relations 
and uses. On many fishes, particularly of the Salmonide, a 
portion of the masseter muscle forms a rounded, fleshy mass, 
which can be detached from the remaining body of the muscle 
with considerable facility. Perhaps the organ on the cheek 
of Malacosteus represents this fleshy mass. But if so, why 
are its fibres so extremely minute? Why does it assume this 
perfectly separate, ovoid form and isolated position? And 
above all, why does it undergo a change which muscular fibre 
nowhere else undergoes, becoming by the action of alcohol, 
like the crystalline lens ? 
We can but leave the matter in this state of uncertainty, 
and trust that the discovery of other specimens may enable 
observers to decide the point. 
The whole fish is covered with a smooth skin, entirely des- 
titute of scales, or of any traces of their development. 
The color in all parts is black. 
The pectorals are situated beneath the body, one inch and 
five-tenths from the tip of the lower jaw. They consist of 
five rays, so united as to seem, except under a magnifier, like 
a single filament. "The external ray is very short, the second 
is about three-eighths of an inch in height. "The third and 
