STRUCTURE OF BIRDS. 53 



portion hidden in Fig. 4 ; 6, the rectum, cloaca, and coeca ; 7, 

 the internal surface of the proventriculus ; 8, part of a section 

 of that organ; 9, four of its glandules; 10, a portion of the 

 inner surface of the stomach ; 11, the pylorus, or commence- 

 ment of the intestine. 



The bill of the Peregrine Falcon, Plate IV, Fig. 1, is shorter 

 than the head ; the upper mandible, a, has at the base a cere, ^, 

 or bare coloured skin, of a peculiar dense texture, closely re- 

 sembling that of the scales on the feet ; its dorsal outline, c, is 

 slightly convex, as far as the edge of the cere, then curved so 

 as to form about the third of a circle ; the ridge on the cere is 

 broad and convex, on the horny part narrow^er but convex ; the 

 sides at the base are nearly flat and sloping, towards the end 

 more erect and convex ; the edges towards the base, d^ are soft, 

 being covered with skin, continuous with the membrane of the 

 mouth, beyond the nostrils sharp, hard, and projecting towards 

 the end, so as to form a thin rectangular process, which is 

 characteristic of the genus Falco ; the tip decurved, subtri- 

 gonal, acute. The mouth being wide, the lower jaw, e, has its 

 rami widely separated at the base, so that the angle formed at 

 the base of the horny mandible, f, is broad and rounded ; its 

 dorsal outline, ^, is convex, the back broad, towards the end 

 narrowed ; the sides rounded ; the edges at the base covered 

 with skin, towards the end horny, inflected and sharp, with a 

 deep sinus or notch near the tip, which, viewed vertically, is 

 truncate. The process of the upper mandible is represented 

 by many ornithologists as entering the sinus of the lower, 

 which, however, is not the case, as it merely overlaps that part 

 of the low^er mandible on which it is situated. 



The palate. Fig. 2, is flat, at the sides smooth, and sloping a 

 little upwards, in the middle bearing a longitudinal depression, 

 «, a, into which the tongue fits. This depression is bounded by 

 two nearly parallel ridges of skin. In it, behind the base of 

 the tongue, is the narrow, posteriorly sub-elliptical aperture of 

 the nares, ^, of which the anterior slit, ^, extends forwards 

 nearly to its termination. At the commencement of the slit 

 behind is on each side a curved papillate line or edge, d ; and 

 behind the aperture is another, ^, having several rows of 



