192 Wetmore, The Palate in Icteridce. [ April 



In birds that are almost fully feathered and that are about ready 

 to leave the nest the bill has become stronger, the raised palatal 

 line is heavier, and has a rounded anterior end that forms a marked 

 projection and then continues to merge with the palate in front. 

 In older specimens, able to fly but with the rectrices only 95 to 

 105 mm. long, the palatal ridge was better marked, being broad 

 and strong basally and more slender toward the point. In a few 

 of the specimens of this stage examined the cutting angle seemed 

 well developed, but in others it was less strongly indicated. In 

 birds that were fully grown but still in juvenal plumage the ridge 

 was well developed but not so prominent as in adults. In some 

 the basal portion was broad and rounded, verging toward the 

 formation of palate found in the genus Mcgaquiscalus. In others 

 the anterior cutting angle was more prominent but the entire ridge 

 had only attained from one-half to three-fourths of its full height. 



No one apparently has raised the question of the possible function 

 of this keel, developed as described above, so that it seems proper 

 to record here certain field observations made by the writer that 

 indicate the use of this structure. As might be expected it serves 

 in securing and preparing certain parts of the food. In December 

 1917, near Stuttgart in eastern Arkansas, during a time when the 

 ground was covered by a light fall of snow, flocks of Bronzed 

 Grackles were found feeding among small groves of a pin oak 

 (Quercus pagodaefolia) . The ground under these trees was nearly 

 bare and the birds were working about searching for the small 

 acorns that had fallen and were partly concealed under leaves 

 and low plant growth beneath the oaks. The Grackles were tame 

 and with a pair of binoculars it was an easy matter to watch them 

 at close range. The acorns were picked up, held in the bill and 

 pressed firmly against the keel on the palate, then released, turned 

 slightly by means of mandibles and tongue, and then again gripped 

 strongly. In this way the acorn was rotated until a line had been 

 impressed entirely around the shell. With a little further manipu- 

 lation the shell dropped off in two halves and the kernel was swal- 

 lowed entire without further preparation, though frequently it 

 was gulped down only after some effort. After watching one feed- 

 ing flock for some time I clapped my hands sharply to startle them 

 and then examined the ground where they had been at work. 



