EXTEBNAL PABTS OF BIRDS. — TOPOGRAPHY. 97 



is called • cervical collar," to distinguish it from tho guttural or jugular "collars" or rings of 

 (•(dor. Nucha is frcMiuently similarly marked with a "nuchal band;" often special develop- 

 ments there take the form of lengthening of the feathers, and we have a " nuchal crest." More 

 particularly in birds of largely variegated colors, guttur and jugulum are marked lengthwise 

 with stripes and streaks, of which those on the sides are apt to be different from those along 

 tile middle line in fnmt. Jugulum occasionally has lengthened feathers, as in many herons. 

 Higher up, the neck in front may have variously lengthened or otherwise modified feathers. 

 Conspicuous among these are the ruffs, or tippets, of some bu'ds, especially of the grebe family 

 (Podicipedidae), and, above all our other birds, of the male ruff (MacJietes pugnax). But 

 these, and a few other modifications of the feathers of the upper neck, are more conveniently 

 considered with th()ye of the 



Head. — Though smaller than any of the areas already considered, the head has been 

 more luinutely mapped out, and much detaQ is required by the number and importance of its 

 recognizable parts or regions. Without intending to mention all that have been named, I 

 describe all needed to be known for any practical purposes. 



" Top of the head" is a collective term for all the upper surface, from base of bill to 

 nape, and laterally to about the level of the upper border of the eyes; this is the pileum or 

 "cap" (fig. 25, 1, 4, 6) : it is divided into three portions. The forehead, or frontal region, 

 or simply " the front " (Lat. frons ; fig. 25, 1), includes aU that slopes upward from the bill, 

 — generally to about opposite the anterior border of the eyes. Middle head or crown (Lat. 

 corona) or vertex (Lat., fig. 35, 1), includes the top of the head proper, or highest part, from 

 the rise of the forehead to the fall of the hind-head towai'ds nucha. This slope is the hind-head, 

 or occiput (Lat., fig. 25, 6). The lateral border of all three constitutes the superciliary linej 

 that is, the line over the eye (Lat. super, over; cilia, little hairs, especially of the brows). 

 " Crown " is often used as the same thing as pileum. The adjectives of the several words are 

 frontal, coronal or vertical, and occipital : pileum has none in use, coronal being said instead. 



" Side of the head" is a general term defining itself; it presents for consideration several 

 regions. The orhital or circumorbital region, or simply the orbit (Lat. orbis, an orb, here the 

 socket (tf the eyeball; fig. 25, 3), is a small space forming a ring around the eye. It includes 

 the eye, and especially the eyelids (Lat. palpebrce). The points where these meet, in front and 

 behind, respectively, are the anterior canthus and posterior canthus (Gr. Kav66s, kanthos, Lat. 

 canthiis, a tire). The orbital region is subdivided into supra-orbital, infra-orbital, ante-orbital, 

 and post-orbitnl, according as its upper, under, front, or back portion is desired to be specially 

 designated. The situation of the orbit varies much in different groups of birds ; it is generally 

 midway, as said above, but may be higher or lower, jammed on toward the bill, or pushed far 

 up and back, as strikingly shown in the woodcock. In owls, the orbital region is exaggerated 

 into a great disc of radiating feathers, confemng a peculiar physiognomy. The aural or 

 av/ricular (Lat. auris, or auriculum, ear; fig. 25, 35) region lies about the external opening 

 of the ear, or meatus auditorius ; its position varies in heads of different shapes, but it nearly 

 always lies behind and a little below the eye. Wherever located, it may be recognized at a 

 glance, by the peculiar texture of the feathers (the auriculars) which overlie the meatus. 

 Doubtless to offer least obstacle to sound, these are a parcel of loose-webbed little plumes, 

 which may be collectively raised and turned forward, exposing the orifice of the ear ; they are 

 extremely large and iKjtable in those owls which have complicated external ear parts, and in 

 such they form part of the great facial disc. The term " temporal region " or " temple " is not 

 often used in ornithology, not being well distinguished from the post-orbital space between eye 

 and ear, and having nothing special about it. At the lowermost back corner of the side of the 

 head, generally just behind and below the ear, may be seen or felt a hard protuberance ; it is 

 the sharpest corner-stone of the head, being the place where the lower jaw hinges upon the 



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