358 
ON THE CLASSIFICATION OF BIRDS. 
Families of 
Fissirostres. 
Analogies. 
Families erf 
Scaiisores. 
Trooon'id/B. Bill strong, thick, the margin serrated. RAMPHASxiDi 
No one, it is true, would ever mistake a goatsucker for 
a parrot, yet how singularly do they resemble each other 
in some of the most remarkable peculiarities of their 
structure. The facility with which swallows perch and 
retain their hold, in the most perpendicular situations, 
is a power only possessed by climbing birds ; but the 
analogy is carried much farther by a genus of swallows 
(ChcEtvm), whose tails are more stiff and sharp than 
those of the most typical woodpeckers. By comparing 
the hills of any of the South American creepers {T>m- 
drocolaptes), with those of the bee-eaters {Meropidai), 
and we shall he at no loss to discover the analogy of the 
two families ; and this resemblance even extends to their 
feet, the three anterior toes, in each group, being aU united 
together at their base. The analogy between the two 
next families in the table is still more remarkable, for 
not only are the toes of the puff birds (Taviatia) ar- 
ranged like those of the cuckows, but the likeness is so 
strong as to have deceived every naturalist into a belief 
that they were actually united by affinity ; we have 
shown, however, that no two tribes can be more distinct 
in manners and natural economy. They must be kept 
separate in all systems professing to be natural. There 
remains, therefore, but one more comparison, — that 
between the trogons and the toucans : by these two 
families, as we conceive, the Fissirostres and Scansores 
are united. We accordingly find that this is effected 
by the motmots (Prionites), which indisputably present 
not the slightest affinity to the homhills, and yet they 
show the strongest inclination to unite with the Fissiros- 
tres, by means of the Prionites platyrhynchus, and the 
Ckilbula grandis in their own circle. 
(297.) That analogies change, and become inter- 
mixed, in certain groups, according to the position 
occupied by such groups, is a fact we have before 
