16*2 TODUS. 



parative. In Todus platycircus their length is the 

 greatest; while in viridis and megacephalus they 

 are shorter than in melanocephalus. These varia- 

 tions are accompanied by differences in the formation 

 of the claws and toes ; so that without a competent 

 knowledge of the group as a mhole^ " good genera," 

 as such artificial divisions are sometimes called, 

 might actually he made out of several of the species, 

 to the no small confusion of all that is true in 

 nature or useful in science. It has entirely origi- 

 nated, in fact, from such limited views, that the 

 Todus viridis has been pronounced " the unique 

 example cf its genus ;" and ail the other species 

 detached from it, and thrown into the common 

 receptacle of flat-bellied birds," the great genus" 

 Muscicapa. It is needless, however, to critici?^ 

 artificial systems; and therefore let us now see 

 what results will be obtained by arranging tne 

 species above named, and comparing then? witn 

 tne types they represent. 



