VOL. XIX, PP. 101-112 JULY 30, 1906 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON NOTES ON BIRDS FROM COSTA RICA AND CHIRIQUI, WITH DESCRIPTIONS OF NEW FORMS AND NEW RECORDS FOR COSTA RICA. BY OUTRAN BANGS. In the spring of 1905 while Mr. Robert Ridgway was in Costa Rica, Mr. C. F. Underwood offered him for sale his entire col lection of birds. Mr. Ridgway at once wrote to John E. Thayer, Esq., and myself, setting forth the great advantage it would be to American ornithologists to have this collection come to the United States. Mr. Thayer at once bought the collection and in due time it was packed and shipped to us. It consisted of 3,365 skins, representing about 611 species and subspecies mostly from Costa Rica, though a few came from Guatemala. The collection had been kept by Underwood as a sort of type series from which he might name specimens he secured, and many of the skins had been identified by Salvin, the labels bearing names and notes in his handwriting. Besides contain ing representatives of most of the rarer Costa Rican species the collection is rich in young birds in nestling plumage, and where the series of a species is large, specimens both in freshly moulted plumage and in worn, abraded condition can be found. The dates on the labels cover nearly a score of years, and the col lection is the result of Underwood's laying aside the better things secured by him during this period. Such a collection is invaluable. Mr. Thayer turned the whole lot over to me for identification, and with help here and there from Ridgway, Nelson, Oberholser, Richmond, and Riley, I have at last finished the work, which, as usual, took a much longer time than I anticipated. At first Mr. Thayer was undecided what to do with the collection, but, noticing from time to time the great interest I took in it, finally, 24 PROC. BIOL. Soc. WASH., VOL. XIX, 1906.