226 
IIYLTOTA. 
while the breadth of the hill at its base indicates its 
insectivorous habits : its apparently anomalous struc- 
ture, in other respects, is explained by the situation 
it holds as the tenuirostral type of its own genus. 
Hence its bill is the longest, and, like that of 
Monachus, it is considerably compressed ; by the 
absence of bristles, and by the thick feathers on the 
rump, it preserves its analogy to the Cellepyrina , 
or caterpillar-catchers, without diminishing its 
affinity in other parts of its structure to Musci- 
capa, or its analogy in point of colour to Platys- 
tera. Such are the conclusions we have come to 
after some years reflection, and which we have 
elsewhere intimated*. At present we know but of 
one species; the sexes of which, unlike all the 
other types of Muscicapa, differ as remarkably in 
colour as do those of its prototype Platystera. And 
the student will remember, that the tenuirostral 
types are always those which have the most marked 
difference in the plumage of the sexes. The whole 
of the Ampelidce , the order Grallatores, and the 
tribe of Tenuirostres, not to mention the Orioles, 
PsariancE, and several others of minor note, are 
convincing proofs of this general law. It is well 
known, again, that nearly all tenuirostral types have 
the longest bills among their congeners : witness the 
humming-birds and the whole order of waders. "We 
find this analogy, therefore, preserved in the present 
family ; for this is a peculiar characteristic in P saris, 
Perspicilla, Monacha, and Hyliota, groups of dif- 
* Classification of Birds, ii. 
