40 On the Rclalions between the Stnict?ire of the Organ of Voice, 



the tarsal covering of the Ti/rannidae difl'ers from that of the Chmbing Birds 

 (Klettervogel)^ 



Since the AmpcUdae, Tjrannl, Piprae, and Psaris do not possess a vocal larynx, as has 

 been already described, the views of Blasius and Kej'serling are so for supported. 

 CJiasmarhynclniH on the contrary has more muscle on its larynx than any other Singing 

 Bird, but this case alone is not decisive, because of the peculiarity of this organ. In 

 all these birds the anterior series of tarsal plates reaches so far back on both sides, that 

 only an exceedingly small space is generally left ; this is either covered with granules or 

 scales, or is naked. But in birds with a vocal larynx there are, ordinarily, only two postero- 

 lateral scutes, which w'ould then form the essential point of difference, if there is present 

 on the posterior surface of the tarsus a layer of granules between these scutes, as in 

 T,anrns balihaJcii-i and Unhihes relig'wsa ; in which latter the tarsal scutes are also divided 

 from the anterior plates by granules. 



So far the Picarii really appear to be defined by external characters, and we seem 

 to be able to conclude from the presence of the tarsal scutes behind the anterior plates 

 that the muscular vocal larynx is present, and from the extension of the anterior plates 

 to the posterior granulated or naked part, that the larynx of the Picarii is present. 



But yet there are exceptions; the genus LijMugus Boie. In L. plumbeus {^Muscicapa 

 plumhea Licht.) the hinder space is granulated, but one other very similar species of the 

 genus, L. calcarrdus [Ti/ramnda calcarata. Sw.) has a series of jjlates on the outer posterior 

 side of the foot, and the inner posterior side is naked. The genus Gubernetes of the family 

 of FhivicoUnae (with spots on the wings, as the other Fluvicolinae) has, on the posterior 

 part of the foot, two series of plates. The genera ScfopJtaga, 3Iyiohiiis, ArAndinicola (Todm 

 leucocejjJmhis Gm.), and Celopterus Cab. are not Singing Birds, but belong, according 

 to the structure of their larynx, and their external appearance, to the family of the 

 Tymnnidae. However, in the covering of their feet these birds strikingly resemble the 

 Singing Birds, in that they, at least on the outer posterior side of their feet, have a 

 complete space, which extends to the edge of the dorsal side of the pes. 



The most striking exceptions to this rule I find in the characters of the hinder plates; 

 two hinder series of plates may appear (i) in Singing Birds with the muscular organ 

 of voice (Larks); (3) in Picarii {Gubernetes); (3) in Traclicoplwnes [Tkamnophilus, Ctcamaeza, 



> In the last systematic work. The Genera of Birds, hij G. R. Gray, illustrated with 1^0 plates, this coveriiifr 

 of the foot, which is so important in the classification of Genera and Families, is quite overlooked. Swainson 

 had obsened it. 



