Muller’s topknot. 
171 
Another mark of distinction is described as existing in the 
roughness of the under side; but with respect to this we 
hesitate with the expression of a doubt as regards its constancy. 
There are variations of proportion in the parts of the body 
which may be observed when these fishes are brought together, 
but the separation of the ventral fins from the anal in Bloch’s 
Topknot, whereas they are closely joined together in the 
present species, is a more decisive ground of distinction between 
them; although a question may arise whether the not very 
distant separation of these organs should be deemed sufficient 
to consign them, as has been done, to different genera. The 
underlapping of the termination of the dorsal and anal fins 
beneath the body, as here represented, appears to afford a 
more characteristic distinction for constituting a separate genus, 
as distinguishing these two species of fish from all others of 
this family with which we are acquainted, as well in form as 
probably in habit. 
The length of the example described which was of the usual 
size, was six inches and a half, and in width with the fins 
extended four inches and a half; but without measuring the 
fins the breadth was three inches; from the snout to the 
hindmost extent of the gill-covers one inch and six eighths; 
the gape wide, opening downward; the mystache wide, teeth 
small; the lower eye advanced before the upper. The lateral 
line rises in an arch over the pectoral fin, and from thence 
backward straight. The upper surface, as well of the head as 
