222 On the Natural History of 



scansorial creepers; the passage beingfurther 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 Cuculidoe 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 Scan~sor.es. For this purpose, I now offer the following table 

 of the 



Analogies of the Cuculinje. 

 1. Typical Group. 

 n- C Bill somewhat conic, the sides thick and ? n 



CUCULIN..E, , 1 j , (- CONIROSTRES. 



£ rounded, ) 



Sub-Typical Group. 

 r, { Bill compressed ; considerably arched } ^ 



COCCYZIN^E, -J p r ., \ ' .i '.' v , } j (- DENTIROSTRES. 



i from the base, the tip hooked, ) 



Aberrant Group. 

 SaurotheriNjE, Seize their prey from a fixed station, Fissirostres. 



Tenuirostres. 

 , ( Bill short, thick, tarsus shorter than the } a 



iNDICATORINiE, -] ' , . f SCANSORES. 



( outer toe ) 



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 



