104 GENERAL ORNITHOLOGY. 



onl}- meet at the extreme tip, or in the whole duck family, where there is liardly more. As 

 the student niust see, the length of the gonys is simply a matter of how extensive is the fusion 

 of the rami, and tliat, similarly, thou- mode of fusion, as in a sharp ridge, a flat surface, a 

 straight line, a curve, etc., results in cimesponding mtidifications of its special shape. The 

 interramiil space is complementary to length of gonys : sometimes it runs to the tip of the liill, 

 as in a pelican, sometimes there is next to none, as in a pufSn ; while its width depends upon 

 the degree of divergence, and the straightuess or curvature, of the rami. The surface between 

 the tomium and lower edge of rami and gonys together is the side of the under mandihle 

 (fig. 26, m). The most important feature of the 



Upper JIandible is the eulmeu (Lat. for top of anything •. fig. 26, h). The culmen is to 

 the upper mandible what the ridge is to the roof of a house ; it is the upper profile of the Tiill 

 — the highest middle lengthwise line of the hill ; it begins where the featliers end on the fore- 

 head, and extends to the tip of tlie upper mandible. Acconling to the shape of the bill it may 

 be straight or convex, or concave, or even somewhat ct -shaped ; or d(.iuble-convex, as in the 

 tufted pufiiu ; but in the great majority of cases it is convex, with increasing convexity tdwards 

 the tip. Sometimes it rises up into a thin elevated crest, as well shown in the genus Cro- 

 tophaga, and in the puffins (Fmtercida}, when the upper mandible is said to be l-eekd, and the 

 culmen itself to be cultratc ; sometimes it is really a furrow instead of a ridge, as toward tlie 

 end of a snipe's bill ; but generally it is simply the uppermost liue of union <d' the gently con- 

 vex and sloping sides of the upper mandihle (fig. 26, a). In a great many birds, especially 

 tliose with depressed bill, as all the ducks, there is really no culmen ; but then the median 

 lengthicise Une of the surface of the upper mandible takes the place and name of culmen. 

 The culmen generally stops short about opposite the proper base of the bill ; then the feathers 

 sweep across its end, and downwards across the base of the sides of the upper mandible, 

 usually also obliiiuely backwards. Variations in botli directions from this standard are 

 fi-erpieut ; the feathers may run out in a point on the culmen, sliortening the latter, or the 

 culmen may run a way np the forehead, parting the feathers : either iu a point, as in the rails 

 and gallinaceous birds, or as a broad jjlate of honi, as in the coots and gallinules. The loA\er 

 edge (double) of the upper mandible is the maxillary tomium, as far backward as it is hard 

 and horny. The most conspicuous feature of the upper mandible in most birds is the 



Nasal Fossa (Lat. fossa, a ditch), or nasal groove (fig. 26, ci, in which the nostrils open. 

 The upiper prong of the intermaxillary bone is usually separated some ways from the two 

 lateral prongs; the skinny or homy sheath that stretches betwixt them is usually sunken 

 below the general level of the bill, especially in those birds where the prongs are long or 

 widely separated; this "ditch" is what we are about. It is called /oss« when short and wide, 

 with varying depth ; sulcus or groove when long and naiTow ; the former is well illustrated in 

 the gallinaceous birds ; the latter in nearly all wading birds and many swimmers. When the 

 intermaxillary jirongs are soldered thi'oughout, or are very short and close together, there is 

 no (or no evident) nasal depression, the nostrils then opening flush ^■^'ith the level of the 

 biU. The 



Nostrils (fig. 26, d), two in number, vary in position as follows: — they are lateral, when 

 on the .sides of the upper nmndible (almost always) ; culminrd, when together on the ridge 

 (rare) ; svperior or inferior when evidently abo\e or below midway betwixt culmen and tomia: 

 they are hasal, when at the liase of the ujiper mandible; sidj-liascd when near it (usual); 

 median when at or near the middle of the upper nmndible (frequent, as in cranes, geese, etc.) : 

 terminal when beyond this (very rare ; probaldy there are now no birds with nostrils at the 

 end of the bill, except the Apteryx). The no.strils are pervious, when open, as iu nearly all 



