ADDENDUM TO MULLER'S PAPER ON THE VOCAL ORGANS 



OF PASSERINE BIRDS. 



Since this paper has been printed fresh supplies of Singing Birds have been received 

 from Jamaica, Venezuela, Guiana, and Mozambique. Of the American genera without 

 the compound muscular organ, Milvulus Sw. {M. tyrannm Bonap.) and Cyelorlujnclm, 

 Simdev. {Flati/rhpichm flaviventer Spix.) have arrived for examination. The former genus 

 is like Tp-annus, the latter has only one less-developed laryngeal muscle, which is 

 little more than the mere continuation of the lateral muscle. Todus viridis L. has no 

 muscle at all at the side of the larynx. 



The examination of the genera Setophaga Sw. and Mi/iadestes Sw. was of especial 

 interest. Setophaga had not been examined by me before, and there was only the 

 observation of Audubon that S. rutkiUa had merely a single laryngeal muscle, like the 

 Tyrannidae. As such, I had therefore placed it in the list of birds without the complex 

 vocal muscles, and had also supposed that this genus was closely allied to the singing 

 genus S^hicola. I am now convinced, by the examination of several examples oi Setophaga 

 ruticilla, that the results of Audubon are incorrect as regards this bird. Although its 

 laryngeal muscles are comparatively feeble, yet they are distinctly arranged in an anterior 

 and a posterior portion, so that SetopJiaga agrees, in the structure of its larynx, with 

 S^hicola and the Singing Birds in the true sense; this genus must be struck out from 

 the list of birds without the complex vocal muscles, and be placed with the birds which 

 have them. Their systematic position is not in the family of the Tyrannidae, but with 

 the Si/hiadae, and further close to Sijlvicola. 



Myiadestes Sw. is also a true Singing Bird, with the complex arrangement of singing 

 muscles. I examined M. genibarlis, which is the type of the genus. This genus is very 

 closely allied to Ptilogonys Sw. Gray formerly placed Mpadestes among his Musckaphtae, 

 and Ptilogonys among his Campephaginae {'A List of the Genera of Birds'). In his later 

 work ('The Genera of Birds ') he has united both genera, and they are in fact very closely 

 allied, if not identical. In any case it is now very probable that the type of the genus 

 Piilogonys, Ft. cinereus Sw., wHl also have the muscular organ of voice. Cabams placed 



