1877.] ON THE ANATOMY OF PASSERINE BIRDS. 523 



generis) albo : remigibus fusco-nigris, primariis internis media- 

 liter albidis : specula atari albo : rostro et pedibus brunnes- 

 centibus : long, tola 1 7, alee 7*8, caudcB 2'3, rostri a rictu 2, 

 tarsi r4, dig. med. cum ungue 2'3. 

 Hab. Peruvia occidentalis, prope Lima {Nation). 

 Mus. S.-G. 



Obs. F. collari forsan affinis, sed speculo alari albo nee griseo, 

 genis et gutture rufescentibus facile distinguenda. 



A specimen of tbis curious duck was received by Mr. Sclater 

 from Prof Nation by post ', in January last. In a subsequent 

 letter Prof. Nation says that it is found occasionally in tbe fresh- 

 water lakes near Lima, in company with Querquedula cyanoptera, 

 and Dafila bahamens'ts. The example sent is a female ; and Prof. 

 Nation believes the colouring of the plumage in both sexes to be 

 alike. The irides are of a brownish red, the bill and tarsi brownish. 



9. Notes on the Anatomy of Passerine Birds. — Part III. 

 By A. H. GarroDj F.R.S., Prosector to the Society. 



[Received June 1, 1877.] 



(Plate LIIL) 



On the present occasion I take the opportunity of describing the 

 voice-organ in some species of the non-oscinine (mesomyodian) Pas- 

 seres in which that structure is, so far as I am aware, unknown. 



Leaving any deductions until I have recorded the nature of the 

 structures, I will commence with an account of the syrinx in some 

 of the Tracheophonae. 



Hylactes megapodius. — In this species the syrinx is not identical 

 with any of those described by J. Midler'^. It does not differ much 

 from those of Scytalopus indigoticus and Chamteza brevicauda in its 

 essential structure. By Miiller, however, no mention is made of a 

 peculiarity which I find in this species, which seems to me to throw 

 some light upon the method of development of the tracheophone 

 syrinx. This consists in the way in which the characteristic very 

 slender rings of the specialized voice-organ, instead of ceasing abruptly 

 at its upper end, continue upwards on the anterior surface of the 

 trachea for a considerable distance, whilst posteriorly they suddenly 

 change their breadth superiorly where the syrinx ceases. Figures 

 4 and 5 of Plate LIII represent the anterior and posterior views of 

 the organ. 



The processus vocales, which rest on the first and second modified 

 and ossified bronchial semi-rings, extend up as far as the tracheal 

 true ring, twelfth from the bottom. These twelve lowermost tracheal 



^ By the same conveyance Prof. Nation has also recently sent us the skins of 

 Eallus virginianus (previously not known so far south, see P. Z. S. 1868, p. 445), 

 Lampropsar warcewicHi { = Quiscalus cpquatorialis, Scl.), Ehodopis vesper, 

 Myrtis fannii, and Thnumastura cora, all from the vicinity of Lima. 



^ Abh. Akad. der Wissenschaften zu Berlin, 1847. 



