397 



SIBILATRIX. CHIRPER. 



The genus to which I give the name of Sibilatrix, or Chir- 

 per, is composed of a few species of birds having a very slender 

 form, and remarkable especially for their hideling habits, and 

 peculiar sibilous cry, which, in one species has been compared 

 to that of a Grasshopper or Mole Cricket. They differ from 

 the species of the genus Calamoherpe in having the (bill longer 

 and more compressed, the tarsi and toes also more elongated, 

 while the claws are shorter but more attenuated, and the tail 

 larger and graduated. 



Bill of moderate length, straight, very slender, slightly 

 broader than high at the base, much compressed toward the 

 end ; upper mandible with its dorsal outline sloping a little, 

 toward the end convex, the ridge narrow at the base, broader 

 beyond the nostrils, the edges a little inflected, the tip very 

 narrow, the notches slight ; the lower mandible with the angle 

 rather long and very narrow, the sides convex, the edges in- 

 flected, the tip acute ; the gape-line nearly straight. 



The nostrils linear-oblong, pervious, in the fore part of the 

 nasal membrane, which is feathered behind. Eyes of mode- 

 rate size. External aperture of the ears large and roundish. 



The general form is slender and delicate, the neck rather 

 short, the head ovato-oblong, flattened above, very narrow be- 

 fore. The feet of moderate length, slender ; the tarsus rather 

 long, extremely compressed, with eight large distinct anterior 

 scutella, and two longitudinal plates behind, meeting so as to 

 form an extremely thin edge. Toes extremely compressed, 

 the second and fourth equal and rather long, the hind toe 

 large, but with its claw not so long as the third and its claw, 

 the fourth united as far as the second joint. Claws rather long, 

 moderately arched, extremely compressed, laterally grooved, 

 very acute. 



