Genus— C OPROTHERES. 
CoPROTHERES Reiclienbach, Nat. Syst. Vogel, p. v., 
1852 . . . . . . . . . . . . . . Type C. pomarinus. 
Medium-sized Skuas, with strong bill, long wings, strong legs and feet and 
short tail, with the two centre tail-feathers elongated and twisted, but broad. 
I cannot follow the reasoning that would separate this bird generically from 
Gatharacta and include it in the same genus as members of the genus Ster- 
corarius. In the Cat. Birds Brit. Mus., Vol. XXV., p. 314, 1896, Saunders 
differentiated two genera thus : Megalestris ( = Gatharacta mihi). Size 
larger, form robust ; depth of the bill at the exposed base nearly equal to 
the length of the cere; tarsus rather shorter than the middle toe with its 
claw ; tail short, the central pair of rectrices projecting about 0.5 inch. 
Stercorarius — Coprotheres and Stercorarms mihi). Size smaller, form more 
slender ; depth of the bill at the exposed base decidedly less than the length 
of the cere ; tarsus distinctly shorter than the middle toe with its claw ; 
central pair of rectrices projecting 3 inches or more in adults. 
In the last diagnosis, “ tarsus shorter ” should read “ tarsus longer.” 
This Skua, which I separate generically as Coprotheres, is intermediate 
between Gatharacta and Stercorarius, but cannot fairly be allocated to either. 
It differs from members of the genus Gatharacta in its less stout bill and smaller 
size, and in the elongated central tail-feathers ; from members of the genus 
Stercorarius it differs in its stouter bill, larger size, stronger legs and feet, and 
in the elongated tail-feathers being broad to the tips and twisted. The tail 
is more than half the length of the wing. 
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