the Family of Cuculidce. . 221 
lies are united, so as to form a circle ; or, in other words, to point 
out their internal affinities among themselves. I shall then slight- 
ly notice their external affinities, or those relations by which they 
are united to the conterminous families of the Scansores, that is, to 
the Certhiadce on one side, and to the Ramphastidw on the other. 
First, as to their internal affinities. The progression from the 
Cuculmae to the Coccyzince, or from the parasitic to the building 
cuckoos, is so gradual, that our only difficulty is to discover the 
precise point of their junction, or, in other words, which is the scan- 
sorial type of each, for by these are all circles invariably united. 
One of these appears to be the Cuculus Erythropthalmus of authors. 
From the genus Coccyzus of M. Vieillot, the natural series passes 
into Crotophaga, by means of the Cuculus guira of Linnaeus, rank- 
ed by some as a Coccyzus, and by others as a Crotophaga. By this 
genus, (the fissirostral type,) we leave the Coccyzince and enter the 
aberrant circle by means of the singular bird we shall subsequently 
describe, and which at the same time opens a passage to Phaenico- 
phaus : then follows Leptosomus and Saurothera, two remarkable 
genera, which all writers have kept together. After these, I am dis- 
posed to place the genus Opisthocomus, yet with a mark of doubt, 
not having at this time the opportunity of minutely examining cer- 
tain parts of its structure. Whether or no the Coccyzus Geoff royi of 
the PL Col. pi. 7> and the Cocc. Delalandi of the same work, PI. 
440, two birds nearly as remote from the type of the family as is 
Opisthocomus, really belong to this particular group, remains for fu- 
ture investigation. The last division is only represented by a single 
genus. This is composed of the well-known honey-guides of Africa : 
fortunately, however, the affinity between this and the genus Eudy- 
namys is sufficiently apparent to leave us in no doubt that they fol- 
low each other, and by this affinity we once more return to the ty- 
pical genus Cuculns, and close the circle. 
The external affinities of the family will be found to strengthen 
what has now been said on its internal relations. The Cuculidce, as 
being the most aberrant form of the Scansores, is consequently that 
by which the order Insessores is united to the Rasores, the two 
other aberrant divisions, as before remarked, leading to the Ram- 
phastidoe or toucans on one side, and to the Certhiadce or creepers 
on the other. When we find the Saurotherce, therefore, with large, 
serrated, and hollow bills, we see at once the mode in which na- 
ture has united the structure of a cuckoo with that of a toucan, 
while, on looking to the honey-guides, we detect indications of that 
rigidity in the tail-feathers, about to be fully developed among the 
