aves ardeid^. 377 



General description. 



St'^e.— Adult male. (P. U. O. C. 8638, La Plata, Argentina, July 

 1896, S. Pozzi). 



Total length, about 37.0 inches. 



Wing, 18.7. 



Culmen, 6.0. 



Tail, 7.2. 



Tarsus, 7.3. 



The adult female is larger than the adult male. 



Total length, about 40.0 inches. 



Wing, 18.6. 



Culmen, 5.9. 



Tail, 7.3. 



Tarsus, 7.2. 



Co/o/^. — Adult male (cited). General color slaty bluish above, a white 

 neck, black crown and areas of black on the sides. 



Head : Forehead, crown, occiput and sides of face to below tJie eye, blue 

 black. The feathers on the occiput and posterior portion of sides of head 

 lengthened into a long drooping crest reaching far down on the nape. 

 Lower half of sides of face and head pure dead white. 



Neck : White. The feathers of the lower neck greatly elongated and 

 pure dead white, drooping far below the line of the body. The middle of 

 the throat marked with numerous black feathers, together forming a narrow 

 stripe down the throat and reaching to the elongated white plumes. Chin 

 and upper throat pure white. 



Back : Mantle slaty blue. The feathers lengthened and, with dissoci- 

 ated webs, presenting a generally filamentous appearance. Lower back 

 lighter bluish grey ; rump shading into darker and the upper tail-coverts 

 slaty bluish. The scapulars developed into long pendant plumes, broad 

 at the base, and with the webs somewhat dissociated and becoming 

 narrow and pointed at the ends. These feathers are slaty blue at the 

 base and shade in the narrow pointed part to silvery greyish white. 



Tail : Rectrices dark slaty blue, shading into much lighter terminally. 



Wings : Upper wing-coverts slaty blue, the outer ones of all the series 

 externally silvery greyish white. Bastard-wing, primary-coverts and 

 quills black, with a smoky tinge. The inner secondaries slaty blue 

 externally and the innermost of these feathers wholly slaty blue like the 

 back. The edge of the wing conspicuously white. 



