290 NA UCLERUS FORFJCATUS. 



marshes of the Everglades, where it resides throughout the year, but it also occurs in all 

 the fresh water marshes of Middle and Southern Florida. 



GENUS III. NAUCLERUS. THE FORK-TAILED KITES. 



GEN. Cn. Bill, short, well curved, with the cuttiny edye of upper mandible not lobed. Tarsus, not long and nearly nak- 

 ed. Tail, very deeply emaryinate, exceeding in length one half the length of the wings which, are considerably elonyated. 

 There is no ruff on the face. 



Members of this genus have no ruff, or facial disk, nor are the ear cavities strikingly large. The leg is short and the 

 tarsus is nailed to the heel behind, but is slightly feathered in front. The claws are quite short but pointed. Only one 

 outer quill is noticeably incised on the inner webs. 



The trachea is flattened throughout. The sterno-trachealis is short, having its origin about '25 from the larynx, and 

 there is aslender bronchialis extending overallthe halfrings, but there are no other laryngaal muscles. The tympaniform 

 membrane is present and although there is a thin os transversale, it does not support a semilunar membrane. The walls 

 of the oesophagus are thin; this is at first nearly straight, but is not dilated into a crop, thus forming a striking exception to 

 the rule among bird* of this order. It opens into a rather small proventriculus with simple, oval glands arranged in a zon- 

 ular band which measures I'OO vaforficatus, from which this and the following dimensions were taken. The stomach is 

 of a large size, somewhat globular in form, with thin hut soft walls, and is lined with a soft membrane. The fold c.f the 

 duodenum is long, measuring 3'00, inclosing a narrow pancreas which extends its entire length. There are no traces 

 whatever of any cooca on either side of the intestine. The spleen is an elliptical body lying directly on the proventriculus. 

 Both lobes of the liver are short and thick, hut the left is larger than the right. The heart is large and not very pointed. 

 Sexes, similar in color. There is but one species within our limits. 



NAUCLERUS FORFICATUS. 



Swallow -tailed Kite. 

 NauderusforficMus RIDCW., B. B. R., N. A. Birds, IH; 1874, 192. 



DESCRIPTION. 



Sp. Cn. Form, rather slender. Size, medium. Sternum, rather stont, with the marginal indentations varying with 

 age. Tongue, short, not very fleshy, and about the same width for nearly its entire length, then gradually rounded and bi- 

 fid. Bill, rather short. Feet, comparatively weak, with short claws. Tail, very deeply forked, the outer being nearly 

 twice the length of the middle. 



COLOR. Adult. Head and neck all around, under portions, including under wing coverts, under tail covert?, and tib- 

 ia, middle of back, basal portion of a large part of tertiaries and of a small part of secondaries, white, with the shafts of the 

 feathers on the head, neck, and breast, black. Remainder of upper portions, including wings, upper tail coverts, and tail, 

 black, glossed with green. 



Young, Similar to the adult but somewhat less green on the black above which is also a little duller, and the tail is 

 not as long. 



Nestlings. Are at first covered with a yellowish down, then gradually assume the plumage last described. Bill, black, 

 cere, green, eyes, dark-brown, feet, light-blue, in all stages. 



OBSERVATIONS. 



There appears to be but little variation in specimens of the same age. Known from all other species which occur with- 

 in our limits by the long, very deeply forked tail and by the colors as described. Distributed, as a summer resident, 

 throughout the Southern States, north to Virginia. Rare in the Middle States and accidental in Western Massachusetts. 

 Winters in Central and South America. 



DIMENSIONS. 



Average measurements of male specimen^ from Southern United States. Length, 22-00; stretch, 46'00; wing, 15'00; tail, 

 12-50: bill, 1-00; tarsus, 1-10. Longest specimen, '23-00; greatest extent of wing, 47-00; longest wing, IC'OO; tail, 13 00; 

 bill, l''J5; tarsus, 1-20. Shortest specimen, 21'00; smallest extent of wing, 45-00; shortest wing, 14'00; tail, 12'00; bill, MO; 

 tarsus, 1-15. 



Average measurements of female specimens from Southern United States. Length, 24'50; stretch, 51-00; wing, IG'OO; 

 tail, 13-00; bill, TOO; tarsus, Mo. Longest specimen, 25'50; greatest extentof wing, 5T50; longest wing, 17-00; tail, 1-VOO; 

 bill, 1-25; tarsus, 1'35. Shortest specimen, 23-53; smallest extent of wing, SO'OO; shortest wing, 15'00; tail, 12'00; bill, MO; 

 tarsus, 1-20. 



