V ° 1 'l9l9 Xyi ] Wetmore, The Palate in Icteridce. 191 



Museum, there have been available suitable specimens represent- 

 ing all of the leading genera with the exception of Clypeicterus, 

 Ocyalus, Lampropsar and Macragelceus. In all, one hundred and 

 thirteen species belonging to thirty-one genera have been examined. 

 Study of skins of the genus Quiscalus shows that the palatal keel 

 is developed as a compressed projection from the roof of the mouth, 

 slightly behind the center of the commissure (Fig. 1). Viewed 



Fig. 1. Head of Quiscalus guiscula aeneus. a Palatal keel (about natural aize.) 



from the side it is truncated in front, forming an angular projection 

 that has a tendency to become toothed at the tip. Posteriorly it 

 lowers to merge finally into the level of the palate. The anterior 

 margin is sharp, and the posterior portion is thicker and stronger. 

 The entire ridge is developed as a fold in the horny sheathing of 

 the palate, and the surface of the premaxilla underneath is smooth 

 and flat with no indication of a bony ridge to support the keel. 



From the examination of museum skins it appears that the palatal 

 ridge begins to develop in juvenile birds a short time before they 

 leave the nest, at a stage when the body is well covered with 

 feathers, and the incoming tail feathers have attained a length of 

 20 to 25 millimeters. In such birds the keel appears as a very 

 slightly raised ridge that forms a distinct line on the palate. The 

 bill at this time has reached about three-fourths of the length 

 attained when the bird is adult, so that the beginning of this ridge 

 appears to be located far forward, though it occupies the same 

 position in relation to the external nasal opening that the fully 

 developed keel does in the adult. In the dried skins the ridge is 

 somewhat indistinct, but it is possible that it may be more readily 

 apparent in living or recently killed specimens. 



