SILK BrNTINGS. 9 



membranes may be heard and clearly recognized in the songs 

 of the Robin and White-throated Sparrow. 



There is considerable variation in the size of these mem- 

 branes and in their governing muscles in the various genera 

 of this family ; as a rule the divisions of the muscles are not 

 as shapely defined as in the typical specimen given, which is 

 that of a Crow. One of the most extreme variations in the 

 larynx may be seen in the Evening Grosbeak as given under 

 that species. 



Genus. SILK BUNTINGS. Spiza. 



Bill, rather thick, but not especially Finch-like. Wings, 

 very long and pointed. Tail, short and not forked, but slight- 

 ly emarginate. We have one species. 



Black=throated Bunting. 



Spiza Americana. 

 Plate I, fig. 1 



Male. General color, ashy yellow above, tinged with 

 greenish, and streaked with dusky ; chestnut on upper parts 

 of wings, brown on remainder and tail. White beneath, line 

 over 63^6 and on lower jaw, middle of breast, under wing 

 coverts and edge of wing, yellow. Triangular patch on throat 

 and small one on back, black. 



Female. Similar, but duller, and the black of breast and 

 throat not as extended. Young male similar to the female. 



Dimensions. Length, 6.75; stretch, 10.75; wing, 3.35; 

 tail, 2.65 ; bill, .55 ; tarsus, .75. 



