672 



U. S. p. R, R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



lanceolate, and reaching nearly its length beyond the tip of the tail, each feather well defined 

 and the wehs not decomposed. 



The body generally in the adult is slaty blue ; the head and neck glossed with bluish purple ; 

 the concealed portions of the feathers purplish brownish red. There is no trace of white on the 

 throat. The bill in life is said to be ultramarine blue at the base, shaded into black towards 

 the point ; the bare space between it and the eye, as well as the edges of the eyelids, ultra- 

 marine. The iris pale yellow ; the legs, tarsi, and toes, black. 



The young bird is pure white ; the head smooth, and the feathers without the decomposed 

 webs. The scapulars are not elongated. The iris is white ; the bill light blue, blackish at the 

 end ; the skin around the eyes and the base of the bill light yellow ; the legs light green. 



Birds changing show a confused patching of white and blue. 



The young bird in white dress is much like the Garzetta candidissima, but is without any of 

 the plumes or crests of the latter species, and almost always shows here and there a trace of 

 blue, instead of being pure white. The middle toe is much longer. The feet are entirely 

 greenish to the claws (livid black in the dry skin) instead of having the toes yellowish, and the 

 base of the bill is without the abruptly defined yellow portion. 



According to Lichtenstein, "the A. caerulea of Linnaeus has the feathers of neck and occiput 

 and the scapulars well defined and linear ; the bill black ; the legs brown, with yellow toes. 

 Length, 18 inches ; bill, 2.50 ; tarsus, 3. Hab. — Cayenne. The North American A. caerulescens 

 has the same feathers with the fibres loose ; the bill whitish at base ; the legs and toes greenish. 

 Length, 22 inches ; bill, 3 ; tarsi, 4." The species he refers to first is evidently a true Herodias. 



List of specimens. 



ARDETTA, Gray. 



Jlrdetla, Gray, List of Genera, Appendix, 1842, 13. Type Jlrdea minuta, L. 



Jlrdeola, Bonaparte, Syn. 1828. Type Jlrdea exilis, L. Not Ardeola, Boie, Isis, 1822. 



Cii. — Bill slender, acute; both mandibles about equally curved. Legs very short; tarsi less tlian middle toe. Inner toe 

 much longest. Claws long, acute. Tarsi broadly scutellate anteriorly. 



Tail of ten feathers. Neck short. Body much compressed. Head smooth ; the occipital feathers somewhat lengthened ; the 

 lower neck bare of feathers beliind. No plumes. Plumage compact, lustrous ; uniform above. Se.xes difierently colored. 



This genus embraces the smallest known species of heron, and has representatives in all 

 quarters of the globe. 



