170 U. S. P. R. R EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
TYRANNUS, Cuvier. 
Tyrannus, Cuvier, Lemons Anat. Comp. 1799-1800, (Agassiz.) 
Tail nearly even, or moderately forked ; rather short erthan the wings ; the feathers broad, and widening somewhat at the 
ends. Wings long and pointed ; the outer primaries rather abruptly attenuated near the end, the attenuated portion not 
linear, however. Head with a concealed patch of red on the crown. 
The species of this genus are especially characterized by their long, attenuated primaries, 
their moderately forked or nearly even tail, and the concealed crest in the crown. Their 
affinities are nearest to Milvulus , from which the tail, shorter than the wings, instead of twice as 
long, or more, will always serve as a point of distinction. The attenuation of the primary 
differs in being less abrupt and not truly linear, sloping gradually, and not hounded behind by 
a notch. I am unable to appreciate any other differences of importance. 
The character and extent of the attenuation of the primaries, the depth of the fork of the tail, 
with the size of the legs and hill, all vary considerably, and may, perhaps, serve as ground for 
further subdivisions. The hill, in particular, varies much in size in the North American species 
from that of T. carolinensis, where the culmen is hut little more than half the head, to that of 
T. dominicensis, where it is decidedly longer than the head, and almost as stout as that of 
Sauropliagus , (Genus 31elittarchus of Cahanis.) 
The North American species of Tyrannus may he arranged by colors, accordingly as they are 
white beneath or yellow, in the following manner : 
A. —Under parts whitish, without any shade of yellow. A grayish plumbeous pectoral 
band. 
Tail slightly rounded. Bill much shorter than the head. Above black, shading 
into dark plumbeous on the back. Tail abruptly and broadly margined and 
tipped with pure white... T. carolinensis. 
Tail moderately forked. Bill longer than the head. Above gray ; the tail and 
wings brownish. The edges and tips of the tail narrowly margined with 
soiled white..... T. dominicensis. 
B. —Above ashy olive, becoming purer ash on the head. Tail brown or black. Beneath 
yellow ; the chin paler ; the breast strongly shaded with olivaceous or ashy. 
a. —Tail nearly black ; the outer edges of the outer webs of the feathers with the fibres 
united closely throughout, and similarly colored with the rest of the feather. 
Tail slightly forked ; external feather with the entire outer web and the outer 
half of the shaft abruptly yellowish white. Pectoral band pale ashy, lighter 
than the back....... T. verticalis. 
Tail nearly even or slightly rounded ; external feather with the shaft brown ; the 
outer edge of the outer web only obscurely yellowish white. Throat and breast 
broadly tinged with dark ashy olive like the back. T. vociferans. 
b. —Tail brown, scarcely darker than the wings ; outer edges of the outer webs of the 
tail feathers olivaceous like the back, in contrast with the brown ; the fibres loosened 
externally ; shafts of tail feathers white beneath. 
Tail quite deeply forked ; (depth .65 of an inch); dark brown; the posterior upper 
tail coverts nearly similar. Wing feathers edged with yellowish. ..T. melancholicus. 
Tail moderately forked ; (depth .30 of an inch) ; light brown ; posterior upper 
tail coverts scarcely less olivaceous than the back. Wing feathers edged with 
grayish white....... T. couchii. 
