32 Mr. H. Seebohm on the 



Caprimulgine arrangement, whether typical or Alcedine, the 

 hallux is contracted by the front plantar. 



I therefore propose to associate the synpelmous Picariae 

 in an Order by themselves, and consequently to exclude them 

 from the Pico-Passeres. 



Pico-Passeres. 

 The Pico-Passeres contain nearly half the species of 

 existing birds, and are, on the whole, the most highly deve- 

 loped. In the arrangement of their palatine bones they 

 are generally segithognathous, but some of the more aberrant 

 families contain species which are schizognathous, desmo- 

 gnathous, or saurognathous. Of the innumerable characters 

 which they all possess the following appear to be specially 

 valuable for their diagnosis : — 



1. They have no ambiens muscle. 



This character excludes all birds except the Podicipes, the 

 Striges, the Alcidae, the Syndactyly and some of the Casuarii, 

 the Psittaci, the Tubinares, the Col um bye, and the Hero- 

 diones. 



2. The myological formula of the muscles of the thigh 

 is AX or AXY (the accessory femoro-caudal is never present, 

 whilst the femoro-caudal and the semitendinosus are never 

 absent) . 



This character excludes the Casuarii, the Striges, the 

 Podicipes, the Columbae, and many other birds. 



3. In their pterylosis the spinal feather-tract is never 

 interrupted by a naked tract on the hind neck. 



This character excludes the Herodiones. 



4. In the arrangement of the deep plan tars, the hallux is 

 always in direct connection with the hind plantar. 



This character excludes the synpelmous Picariae, or Syn- 

 dactyli. 



5. The dorsal vertebrae are all heteroccelous. 



This character excludes the Psittaci, the Gavio-Limicolse 

 (of which the Alcidae are a family), and some other birds. 



6. They have no supraorbital fossae for the reception of 

 the nasal glands. 



