Gentjs—L EPTOPH^THON. 
Leptoph^thon Mathews, Austral Avian Record, Vol. II., 
p. 56, 1913 . . . . . . . . . , . . Type L. dorothece. 
Lepturus Reichenbach, Nat. Syst. Vogel, p. vii., 1852 . . Type L. lepturus, 
(Not Lepturus Brisson, 1760, nor Swainson, 1838.) 
Small Phsethons with strong bills, long wings, long tail, small legs and feet. 
In general features the species of this genus agree with ScceophcBtJion, but 
they differ appreciably in size. Proportionately the wing and tail are much 
longer, the tail being differently formed. 
In Scceophcethon the culmen is more than half the length of the tail 
without the central pair of tail-feathers, which is less than one-third the 
length of the wing. In Leptophcethon the culmen is less than haff the length 
of the tail as above, which is more than one- third the length of the wing. 
The central tail-feathers in Leptophcethon are very long with the webs 
normal and fairly wide, and the pair next to the central pair are long and 
are twice the length of the outside pair, the tail being thus strongly wedge- 
shaped. In Scceophcethon the central pair are very long, but the webs are 
degenerate and are scarcely broader than the shaft, while the tail otherwise 
is wedge-shaped but without much gradation. 
The metatarsus is less than a quarter of the length of the tail in 
Leptophcethon^ while in Scceophcethon it is more than one-third. 
The middle toe is never pectinate in this family. 
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