Pico-Passerine Group of Birds. 35 



be) on each side of the posterior margin of the sternum. 

 The arrangement of their plantar tendons is precisely the 

 same as that of the Passeres. The fact that, like the Buc- 

 conidae, the Galbulidae, the Rhamphastidae, and many of the 

 Capitonidae, they are desmognathous, cannot be regarded as 

 of much importance ; but it must be admitted that they are 

 not at all Passerine in their pterylosis. The spinal feather- 

 tract has an interscapular fork, as in Cypselus, Caprimulgus, 

 Coracias, &c. ; and the infei'ior tract is completely forked on 

 each side of the breast, as in most of the Scansores. To find 

 a combination similar to that of Upvpa, it would probably be 

 necessaiy to descend as low as the Gfavise or Limicolae. 



Scansores. 



The Scansores are a clearly defined group of birds, per- 

 haps nearest allied to the Trogons, but having so many 

 characters in common with the Upupae, the Eurylaemi, and 

 the Passeres, that they may be associated with them in an 

 Order. 



So far as is known, the Scansores are the only birds in 

 which the front plantar (flexor perforans digitorum) leads 

 only to the third digit (the middle toe of anisodactyle birds, 

 or the outer front toe of zygodactyle birds) . This character 

 alone is therefore sufficient to diagnose the Scansores ; but 

 the further character may be added that they are zygodactyle 

 [i. e. the outer front toe, or fourth digit, is reversed, and 

 becomes the outer hind toe) . The latter character, however, 

 is not confined to the Scansores, but is also found in the 

 Pseudo-Scansores (Coccyges, Musophagi, Striges, and Psit- 

 taci), and to some extent in Pandion and Leptosomus. 



In the arrangement of their palatal bones the Scansores 

 vary in a remarkable manner. The Indicatoridae resemble the 

 Passeres in being aegithognathous ; the Capitonidae are, some 

 of them, aegithognathous and some desmognathous; thePicidse 

 are schizognathous, but the split vomer and small maxillo- 

 palatines are so peculiar that they have been called sauro- 

 gnathous ; whilst the Rhamphastidae, Galbulidae, and Buc- 

 conidae are desmognathous. 



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