SOMBRE TIT. 59 



present family we have the original genus of Linnseus, Parus; 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 Pophophanes , 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, with the exception of the Long-tailed 

 and Bearded Tits, which may fairly be placed in distinct genera: 

 the latter does not come within the scope of this work. It is re- 

 markable how modern naturalists have lost sight of the thoughts, by 

 which (it is clear, as pointed out by Agassiz,) our old classifiers were 

 influenced in the formation of orders and genera; the consequence 

 of this is that every few years we have a new nomenclature, founded 

 on the assumption that the previous one was based upon erroneous 

 data. 



Upon this all-important subject the reader will find some excellent 

 and judicious remarks in a paper by Mr. Stimpson, quoted from 

 Silliman's "Journal," in the "Edinburgh New Philosophical Journal" 

 for October, 1860. I will only here make one extract: — "The resto- 

 ration by G. R. Gray, of Boddaert's names in ornithology is another 

 instance. By the discovery of a meagre pamphlet of the eighteenth 

 century, only two or three copies of which now exist, we find ourselves 

 forced to change the generic names of common birds, familiar as they 

 are by long and constant usage." This pamphlet has been lately 

 republished with all its errors. 



The Sombre Tit is an inhabitant of Dalmatia, Hungary, Greece, 

 and South Russia. According to De Selys, it also occurs in Switzer- 

 land. It is found in Palestine and Turkey. Temminck says that it 

 is never found in Austria, nor in fact in any part of Germany. 



In the distribution of colours about the head and neck this bird 

 is very similar to Parus sibiricus, with which it has been indeed 

 considered identical by Keyserling and Blasius, without, however, I 



