Account of Observed Forms of Larynx. 



In Mi/iobius Gray, and Aniudluicola D'Orb. Lafr., no large laryngeal muscles exist ; 

 the lateral muscle of tlie trachea is simply prolonged to the bronchi. In Mi/iohius 

 eri/thmrus Mus. BeroL, the first two bronchial rings are perfect, and the muscle raises the 

 third; \n Anmdinicola leucoce2)hala {Todus leucocejihalus Gm.) no bronchial ring is perfect; 

 the slight prolongation of the lateral muscle is inserted into the second bronchial ring. 

 The cartilago arytaenoidea is present. 



In the Fluvicolae examined by me, the lower portion of the trachea was quite covered 

 by the lateral muscles on its anterior wall; though not ending in a point, they 

 terminate where the broad laryngeal muscles arise, which latter perfectly resemble the 

 same muscles in the Tyranninae, and end, without contracting, on one of the bronchial 

 rings. The posterior portion of the larynx is not covered by the muscle. 



In Fluvicola [Entomophagus) hicolor {MuscicajM hicolor L. Gm., M. albkentris Spix) no 

 perfect bronchial ring exists. The muscle is inserted into the first half-ring. The cartilago 

 arytaenoidea of the memhrana tympaniformls is semilunar. 



The genus Centntes Cabanis belongs to the Fluvicolinac, of which Alauda rnfa Gm. 

 is the type. Tracheal and laryngeal muscles, as in the preceding; the first bronchial ring 

 is perfect. There is a cartilago arytaenoidea. 



(v.) Organ of Voice of the Todinae and Platyrliynchinae, Cab. 



Some of the Todus-like Tyrannidae differ very greatly from the type of this family, not 

 only in the want of the perfect rings in the bronchi, and their flattened commencement, 

 but also in the absence of the cartilago arytaenoidea in the memhrana tympanifornm. To 

 such belongs the new genus Colopterus Cabanis, for example, which is characterised and 

 easily known by the first three or four primaries being much shorter than the rest. Our 

 Museums here possess two species of this genus, which have been described by Cabanis 

 in the Archiv fiir Naturgeschichte. The species which I examined, Colopterus cristatus Cab., 

 from Guiana, had the first three primaries short. In this small bird the last twelve 

 rings of the trachea are laterally compressed. It is still more remarkable that these twelve 

 rings are cleft completely behind, and that a small bony clasp, which is connected with 

 the pessulus of the tracheal portion, is placed between the ends of the cleft rings. Not 

 one of the bronchial rings is perfect. The first four half-rings are very broad ; into the 

 fourth the not very broad muscle is inserted; this descends obliquely from before backwards, 

 and ends in a point. A perfectly peculiar muscle is a large azygos one, which shortens 

 the compressed lower portion of the trachea, and reaches as far as the last tracheal ring 



