222 On the Natural History of 
scansorial creepers ; the passage being further manifested by the honey- 
guides climbing with more facility than any other cuckoos. These 
two points of union I therefore consider as established ; because 
they are further confirmed by well-known analogies, too decided to 
be questioned. Nor do I feel any considerable doubt on the situa- 
tion of Opisthocomus ; for whether this curious genus is the grallato- 
rial type of the Cuculidce or of the Cracidce, in other words, the 
last form among the Insessores, or the first of the Rasores, it cer- 
tainly appears a form intermediate between the two orders, and 
bears every mark of being a grallatorial type, corresponding to Gypo- 
geranus. As such I shall consider it, until farther discoveries de- 
monstrate this opinion to be erroneous. 
But before proceeding farther, it is essential to submit this series 
to the same analogical test we have applied to the primary divisions 
of the Scansores. For this purpose, I now offer the following table 
of the 
ANALOGIES or THE CUCULIN.&. 
1. Typical Group. 
a* ^^ tMCk and } CONIROSTRES. 
Sub-Typical Group. 
Aberrant Group. 
SAUROTHERINJE, Seize their prey from a fixed station, FISSIROSTRES. 
TENUIROSTRES. 
INDICATORS, { BiU short ' tU ^^ 8h ^ **" ^ } SCANSORES. 
Where the prototype of a group, which in this case is the tenuiros- 
tral, has not been clearly ascertained, I have been accustomed in 
these analogical tables to leave a blank for its future insertion ; con- 
tenting myself with expressing such opinions on the subject as ap- 
pear, upon the whole, best supported by facts. This plan, it is true, 
is not calculated to impress superficial naturalists with a belief in 
those laws of natural arrangement upon which I have elsewhere 
expatiated ; but it will, at all events, manifest that degree of caution 
in the application of a theory, which is so vitally essential to the pro- 
gress of true science. For this reason I have not chosen to desig- 
nate the tenuirostral type of this family, partly because I feel un- 
certain as to which of the forms already noticed, this title should 
be applied and, secondly, because it involves one of the most im- 
portant affinities in the whole circle of ornithology ; this being the 
point of junction between the insessorial and the rasorial orders. 
But if, upon this question, we are obliged to suspend our judg- 
ment, the very singular and striking analogies which are manifest 
