26 Account of Observed Forms of Larynx. 



with the Muscicapidae, and the latter put Ceplialopterus and Gi/mnocephalus with the Corvidae. 

 The true position of Psaris was very rightly perceived by Cabanis, who has made use of the 

 examination of their vocal organ. Tliytotoma, which has the same covering to the tarsus, 

 is also placed by him in this family ; but I have not examined this genus. 



In the majority of the Amjielinae no considerable laryngeal muscle exists, and the lateral 

 muscle of the trachea is simply prolonged as far as the bronchus, as in the Coracianae, 

 Upupinae, Caprimulginae, most of the Syndactyll, and many Scansores. 



In Ampelis [Cotinga) pompadora the first four rings (half-rings) of the bronchus are 

 broad, and can^ like tiles, be separated from one another ; the very thin prolongation of 

 the lateral muscle of the trachea is inserted into the fifth, which is quite narrow, as 

 are all that follow it. In Bupicola cayana the thin lateral muscle is inserted into the 

 first half-ring, which is quite small. 



In Gymnocephalm calvus the first five half-rings are broad and flat. The thin lateral 

 muscle raises the fourth half-ring. The upper part of the trachea presents the same 

 spindle-shaped widening, as v. Tschudi has described in Cephalopterus. In Psaris cayanus 

 the thin lateral muscle of the trachea extends to the second half-ring of the bronchus ; after 

 which thin half-rings follow. 



The miisculi sternotraclieales ' exist in a very large majority of the singing and screeching 

 Passerines. The genus Pachyrhamphus Gray {PackyrJiynchtis Spix), which is closely allied 

 to Psaris, is strikingly distinguished from Psaris by its larynx ; it is the only genus of 

 the Ampelinae which has a large laryngeal muscle not connected with the lateral 

 muscles of the trachea. 



In PacliyrJiamphus atricapillus Cab. (Piptra atricajnlla Gm., Laiiius mitratus Licht. 

 Doubl. Verz. p. 50), the lateral muscles of the trachea finally turn forwards, and completely 

 cover the anterior wall of the lower j)ortion of the trachea, until they terminate at its 

 end in a common point. The musculi sternofracheales must be regarded, on the whole, as 

 independent muscles, since they generally have no connection with the lateral muscles, but 

 arise, on the contrary, from the sides of the trachea. A peculiar laryngeal muscle arises 

 from the end of the trachea, and is inserted into the second half-ring of the bronchus. 



This condition of the lateral muscles of the trachea I have again found in a genus 

 of the Tyranninae — Pyrocephalus Gould. * 



In Phibalura Jfavirostris Vieill., the elongated thin lateral muscle is inserted into the 

 third bronchial ring. 



' I have only examined the jmusculi sternotrachealee in Eulabes rcligiosa Cuv. and in Trochilus, among the 

 Passerines, Among the Scansores they are wanting, according to Wagner, in the Psittacinae. 



