1889.] MR. p. L. SCLATER ON OPISTHOCOMUS CRISTATUS. 57 



February 19, 1889. 

 Dr. St. George Mivart, F.R.S., Vice-President, in the Chair. 



Mr. Sclater exhibited a series of specimens of the eggs and chicks 

 of the Hoatzin {Opisthocomus cristatus), obtained by iSIr. J. J. 

 Quelch, of the Museum, Georgetown, Demerava, on the Canje Creek, 

 Berbice Eiver, in 1888, and made the following remarks : — 



In 1884 jNIr. E. M. Brigham, in a paper read before the Chicago 

 Academy of Sciences (see 'Ibis,' 1885, p. 118), made some extraor- 

 dinary statements about the condition of the wings in the embryo of 

 the Hoatzin {Opisthocomus cristatus), as observed by him while 

 making " Embryological Studies " in the island of Marajo, on the 

 Lower Amazons. 



Mr. Brigham stated that during the latter portion of the period of 

 incubation, and for several days after hatching, the fore feet, toes, 

 and claws of this bird had the appearance of feet, and afterwards 

 evolved into wings ; he consequently called the Opisthocomus a 

 " quadruped bird." 



When my son went to British Guiana in 1886 I called iiis special 

 attention to tbis subject, and requested him to get me specimens of 

 the eggs and young birds of Opisthocomus for examination. Want 

 of time prevented him from effecting this (sec ' Ibis,' 1887, p. 319) ; 

 and I consequently appUed to Mr. Quelch, the curator of the George- 

 town Museum, to'aid me in this matter, and obtained for him from 

 the Royal Society's Donation Fund the sum of £5, to enable him to 

 undertake the necessary expedition. 



Mr. Quelch most kindly acceded to my request, and made two ex- 

 peditions to the Canje Creek of the Berbice River, in 1888, for the 

 purpose. When he first went there, in March last year, he found 

 the birds abundant, but only just beginning to lay (see ' Ibis,' 1888, 

 p. 378). Mr. Quelch consequently made a second expedition, and 

 writing from the Berbice Hotel on May 24th of that year, announced 

 that he had made a pretty complete collection, consisting of twelve 

 adult birds, a dozen or more of nestlings of different ages, besides 

 chicks and eggs. This series of sfiecimens reached me safely last 

 autumn, aud has been placed in the hands of our Prosector, Mr. F. 

 E. Beddard, for examination. Mr, Beddard is now preparing a paper 

 for ' The Ibis ' on this interesting subject. In the meanwhile I 

 exhibit some of Mr. Qnelch's specimens of the young and eggs. 

 The young, it will be observed, are peculiar for havmg tbe tore 

 Urobs weU°deveioped and the claws on the poUex and index both 

 present aud of large size. According to a paper fay Dr. C. G. 

 Young, recently published in the 'Notes from the Leyden Museum ' 

 (vol. X. July 1888, p. 169, pi. 8), they would seem to use these 

 claws for the purpose of leaving the nest when young and climbing 

 about the branches of the trees. There is thus some foundation for 

 Mr. Brigham's story of the " quadruped bird." 



