2 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 inch; tarsus nine-tenths of an inch. 



The Tits are a very -well-marked 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 

 Linnasus, Partes; then we have Leach separating those 

 with long tails into the genus Mecistura, and those 

 with a beard into that of Calamophilus . Not satisfied 

 with this innovation, Boie calls the last genus Mystacinus, 

 and Vigors places the Little Penduline Titmouse, which 

 I shall figure and describe by and bye, in the genus 

 JEgithalus; while 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 Lophophanes , and the Marsh, 

 Sombre, and Siberian Tits in the genus Pcecilia, 

 while for the Azure Tit he creates the genus Cyanistes, 

 in all of which 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 which (it is clear, as pointed out by 



DSf ! 



