HOOPOES. 



409 



the creepers and sun-birds by most ornithologists of the old scliool, a short review 

 of the chief points in both directions may be in order. 



The following characters are apparently jtasserine. The foot with its long hind 

 toe and the scntclli-]>laiilar tarsus resembles more that of a bird of the next order 

 than one belonging to the present, the more so since the arrangement of the deep 

 plantar tendons is schizo])eImous, or strictly passerine. The posterior margin of the 

 breast-bone is deeply two-notched, unlike most Picarians, though not unknown in this 





Fig. 201. — liMcorvvA abyssinicus^ ground-hornbill. 



order. There is but one carotid, a feature also common to several Picarians. On 

 the whole, the characters which seem to be ])asserine are in the general line of special- 

 ization, and do not with necessity indicate tliat the Passeres have sprung from an 

 Upupoid stem. In other words, it seems more j)rob.able to us that the hoopoes are 

 an extreme sjiccialization of the Picarian type rather than a half-finished Passerine. 

 The chief Picarian features are the desmognathous jialate, pointed manubrial pro- 

 cess of the breast-bone, bifurcation of dorsal tract between the shoulders, tufted oil 

 gland, absence of cscca, syringeal arrangement, besides a number of other characters, 



