188 
PLATYSTERA. 
In proportion to the number of species which 
enter into a group, so do we invariably find a pro- 
portionate degree of variation. Applying this uni- 
versal law to the assemblage of birds forming the 
genus Todus, we observe that as the typical sub- 
genus contains the most in number, so does it ex- 
hibit the greatest variation of structure. Platystera, 
in like manner, ranks the next in extent, and we 
have thus been able to detect three distinct modifi- 
cations of its typical characters. We have no doubt 
that several other species exist of this group ; one 
is obviously the Molenar of Le Vaillant, and we 
suspect the Capuckon llano (PI. 159.) may be an- 
other, although the presence of a crest is much 
against the supposition. All these we have de- 
scribed from the birds before us, but no public or 
private collection, however large, can be supposed 
to contain every thing. We must, therefore, now 
have recourse to our notes, among -which we find 
the following, made some years ago, in the early 
stages of this analysis. “ Platystera is united either 
to Conopophaga or to Platyrhynckus by a bird in 
the British Museum which belongs to Platystera , 
but which has a very short tail; short, unequal, 
and syndactyle toe, formed for perching, and quite 
as much united as those of T. viridis." Here, then, 
is the fissirostral type of Platystera, approximating 
