EIDGWAY ON AMERICAN HERODIONES. 225 



ular plumes. Jugular feathers broad, blended. Culnien about 

 equal to tarsus; tarsus slightly longer than middle toe. Lat- 

 eral outlines of bill concave; gonys nearly straight. Adult 

 and young exceedingly different in plumage. 



11. Nyctherodius. — Size medium. Adult with several ex- 

 tremely elongated linear, compact-webbed occipital plumes. 

 Scapular plumes elongated, narrow, round-tipped, the webs 

 somewhat decomposed. Jugular feathers broad, blended. 

 Culmen much shorter than tarsus (a little longer than middle 

 toe) ; tarsus much longer than middle toe. Color much varie- 

 gated. Lateral outlines of the bill straight ; gonys very con- 

 vex. Adult and young exceedingly different in plumage. 



§§. Malar region entirely naJced. Bill longer than tarsus and 

 middle toe. 



12. AGtAmia. — Size medium. Bill extremely elongated, narrow, 

 and compressed. Adult with greatly elongated, broadly lan- 

 ceolate, acute occipital plumes ; lower back with similar, but 

 more loosely webbed jjlumes overhanging rump. Sides of neck 

 with recurved, sickle-shaped, narrow and acute plumes. Jug- 

 ular feathers broad, blended. Tarsus nearly twice middle toe. 



b. Pectoral and inguinal powder-down tracts united into a continuous 

 strip. 



13. Tigbisoma. — Malar region and throat naked, the latter with or 

 without a medial feathered strip. Tarsus with hexagonal scutellce 

 in front. Outer toe longer than inner; claws short, strongly 

 curved. Plumage much variegated; feathers of neck loose, 

 "fluffy". 



B. Eectrices ten. Tibice loith the loioer portion completely feathered. 

 Pectoral and inguinal poivder-down tracts widely separated. 

 Malar region completely feathered. 



14. Zebrilus. — Size very small (among the smallest of Herons). 

 Plumage exceedingly lax and " fluffy". Bill and feet very small. 

 Culmen about equal to tarsus, both longer than middle toe; 

 outer toe longest. Plumage dull, with transverse undulations 

 of dusky and light fulvous. 



Subfamily BoTAURiN^. 



15. BoTAURUS. — Size medium, or rather large. Sexes similar j 

 young similar to adult. 



16. Ardetta. — Size extremely small (the smallest of Herons). 

 Sexes dissimilar (in all species'?) ; young slightly different from 

 adult. 



Bull. Iv. No. 1—15 



