1887.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 305 



in view of the fact that the former might have developed iu its present 

 habitat from a bUie form, while the latter emanated from an ancestor 

 as gaily decorated as the European Purple Heron. It will be seen 

 how extremely Important it is in such a case to be on the lookout for 

 tbe minutest and even apparently most trifling distinctions; and even 

 so slight a character as the color of the naked portion of the tibise, or 

 the length of the barbs of the scapular plumes may become important 

 facts in distinguishing forms like Hcrodias cgretta aud H. syrmafopkorns. 



Measurements. 



Beyond the fact that a specimen of this form was obtained on Great 

 Liu Kiu during Eodger's Xorth Pacific Exploring Expedition, Decem- 

 ber, 1854, nothing is known iu regard to the occurrence of the White 

 Eeef Heron in Japan. It may easily be overlooked, however, on account 

 of its great similarity to the Egrets, but is easily distinguishable by its 

 generic characters. 



ARDEOLA BoiE. 



1822. — Ardeola BoiE, Isis, 1822, p. 559 (type A. ralloides Scor.). 

 1826. — Buphus BoiE, Isis, 1826, p. 979 (type A. makiccensis Gm.). 

 1829. — Cancropliacjus Kaup, Eutw. Eur. Thierw., p. 42 (tyi)e A. ralloides Scoi'.). 



The Squacco Herons form a very interesting little group of tropical 

 and subtropical species. All of the known species are apparently very 

 much alike in structure and proportions, while the coloration of the 

 adults iu summer is very different. The young and winter birds, of at 

 least five of the known six species (the first five ones of the following 

 synopsis), on the other hand, are so much alike that no characters 

 have as yet been pointed out, which will satisfactorily separate them. 

 For that reason the following synopsis only refers to the adult birds in 

 full breeding plumage. 



Synopsis of the knoicn species of the yenus ARDEOLA. 



<t}. Abdoineu and upper wiug-coverts white. 



¥. Crest-feathers streaked with blackish 1. A. ralloides (ScOP.).* 



* Syn. — 1769. — Ardea ralloides Scopoli, Ann. I Hist. Nat., p. 88. 



1770. — Ardea castanea S. G. Gmelix, Reise RussL, I (p. 165). 

 1770. — Ardea marsigll Lepechin, Nov. Comm. Petrop., XIV (p. 205). 

 1770. — Ardea pumila Lepechix, Nov. Comm. Petrop., XIV (p. 205). 

 1773. — A7-dea comata Pallas, Reise Russ. R., II (p. 715). 

 Proc. N. M. 87 20 



