242 Mr. H. E. Strickland on Upupa and Irrisor. 



This peculiar coincidence of structure must, I submit, be consi- 

 dered to indicate something more than mere analogy, and rather 

 to show that Upiqm and Irrisor form two subdivisions of the same 

 superior group ; or in other words, that they have more affinity to 

 each other than either of them has to any other group which it 

 may resemble. 



Nor are the points of mutual agreement in these two genera 

 wholly confined to the structure of the beak. Considerable as their 

 differences undoubtedly are, yet they are not overpoweringly so. 

 Theyboth nidificate in hollowtrees. Themngs in both are similarly 

 formed, the quills being much gi-aduated, and the fourth and fifth 

 longest. The differences in the style of colom-ing arc not greater 

 than we often meet with in genera of the same subfamily, while 

 the large patcheis of white on the remiges and rectrices of Upupa 

 have their counterparts on the same feathers of Irrisor. The dif- 

 ferences in the form of their tails is a character admitted to be 

 only of generic, and in some genera only of specific importance. 

 The most weighty distinction is midoubtedly to be found in the 

 structure of their feet, but this is not greater than will be found 

 in the feet of many terrestrial genera when compared vaih. the 

 arboreal forms of the same families. If we look at the feet of 

 ground-cuckoos, gi'ound-woodpeckers, ground-paiTots, or gi-ound- 

 pigeons, we shall find that in every case these members are spe- 

 cially modified to suit the habits of the bii'd, yet this modification 

 of the feet does not bhnd us to the time affinities of the species 

 which exhibit it. 



It may be said, that in the present case the evidence of the feet 

 neutralizes that of the beak, and renders it indifferent which way 

 we decide the question. But this is not a correct \dew of the case, 

 because neither the feet of Ujnipa nor of Irrisor present any pe- 

 culiar and unique structure, such as we see in the beaks of both ; 

 they only exhibit a slight modification of the, same organs adapted 

 for special modes of life, and such as are to be met with in many 

 other instances of genera belonging to one and the same sub- 

 family. 



I conclude, therefore, that the true and natural series of affi- 

 nities will be most correctly exliibited l)y preserving Upupa and 

 Irrisor in juxtaposition, and by including them Ijoth in the family 

 Upupidie, which may be divided into two subfamihes, Ujmpiiue 

 and Irrisorina. 



We now come to a more difficult question, viz. what is the po- 

 sition of the Upupidae with respect to the other families of birds ? 

 They certainly are a very insulated group, forming what in geo- 

 logy woidd be termed a remote outlier, and it is not easy to say 

 to which of the more continental masses they most nearly approx- 

 imate. Guided by the elongation of the beak, the majority of 

 authors have placed them unhesitatingly among the Tenuirostres 



1 



