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SOMBRE TIT. 
Specific Characters . — Top of the head, nape, and throat 
brownish black, separated by a broad white band extending from 
the gape to the nape, and increasing in width from before 
backwards. Length five inches and three-tenths; carpus to tip 
of wing three inches; tail two inches and a half; beak from 
gape three-fifths of an incli; tarsus nine-tenths of an inch. 
The Tits are a very wcll-inarkccl family. In dispo- 
sition of colours, in form, and habit, they very much 
resemble each other, in whatever part of the world 
they are found; and yet almost every species is, by 
some author or other, placed in a separate genus. Thus 
in the present family we have the original genus of 
Linnteus, Parus ; then we have Leach separating those 
with long tails into the genus M.ecistura, and those 
with a beard into that of Calamophilm. Xot satisfied 
Avith this innoA’ation, Boie calls the last genus Mystacinus , 
and Vigors places the Little Penduline Titmouse, which 
1 shall figure and describe by and bye, in the genus 
.^yithalus ; AAdiile Brehm places the same bird in a 
genus created for its especial use, that of Pendulinus. 
Then we find that great innovator, Kaup, placing the 
Crested Tit in the genus Lopliojihanes , and the Marsh, 
Sombre, and Siberian Tits in the genus Pmcilia, 
while for the Azure Tit he creates the genus Cyanistes, 
in all of AApich he is followed by Bonaparte. 
This uncertainty arises no doubt from the different 
conceptions by naturalists of what really constitutes a 
genus. As I believe, with Agassiz, that genera are 
natural groups of a peculiar kind, separated from each 
other by ultimate details of structure, I shall consider 
the family of Tits as coming within this definition, and 
therefore as belonging to one genus only. It is re- 
markable how modern naturalists have lost sight of the 
thoughts, by Avhich (it is clear, as pointed out by 
