CHIONIS MINOR. 



91 



DESCRIPTION. 



The first specimen selected for examimition was taken from alcoliol 

 November 5. Tbe field-measurements, from the flesb, are as follows: — 



Plumage universally pure white, very soft and downy. Under plum- 

 age slate-colored. Bill black, stout, conical ; mandibles of equal length. 

 Chord of culmen 1.22, gape 1.35, depth 0.80, width 0.55; depth of up- 

 per mandible 0.37, width 0.40; depth of lower mandible 0.30, width 

 0.55. Commissure nearly straight, with only a slight downward curve 

 towards apex of bill. Lying ovef the upper mandible like a saddle, 

 with tbe pommel tilted up into the air, is the horny black sheath which 

 has given to this bird one of its trivial names. From the insertion oi 

 the frontal feathers to its anterior end, this sheath measures 0.50. The 

 flaps of the saddle project downward and backward below the tomial 

 line, its anterior margin presenting two curves, convex forward, includ- 

 ing one curve, convex posteriorly. The ''pommel" part of tbe sheath 

 projects above the mandible, like a hood, 0.20 inch. From gape to apex 

 the sheath measures 1.00; perpendicular depth 0.70, width of "pom- 

 mel" 0.30, of sheath between lower margin of flaps 0.45. At the sides 

 the flaps are firmly soldered to tbe ui)per mandible, so tbat, in this spe- 

 cies at least, erection of the sheatb (attributed to C. necroj^haga or C. alba 

 by Latham, Lesson and Cuvier,*) is impossible. Structurally contin- 

 uous with tbe sheath, and extending backward and upward from its pos- 

 terior portion, is a thick, black, tumid strip of naked skin, deeply pitted 

 by numerous follicular openings, some of which near tbe edges give pas- 

 sage to hair-like feathers. It lies in contact with the eyelid superiorly, 

 and the portion uncovered by feathers measures 0.55 by 0.30. Upon 

 clipping away the frontal feathers, this black caruncle is found to ex- 

 tend entirely across the forehead, as a squarish frontal hood, covered by 

 white feathers so thickly as to be invisible in its anterior and central two- 

 thirds. Its upper margin (somewhat wider than the lower) is abruptly dis- 

 tinct, just opposite the highest part of the eyelid. The width of the carun- 

 cle at its u[)per and widest part is 1.10; its height from the lowest inser- 

 * Animal Kingdom, Loudon, Oir & Co., 1849, p. 250. 



