Genus — H A L 0 B iE N A . 
Halob^na Bonaparte, Comptes Bendus Sci., Paris, 
Vol. XLII., p. 768, 1856 . . . . . . . . Type H. ccBrulea. 
Za'prium Cones, Bull. U.S. Nat. Mus., No. 2, p. 34, 1875 . . Type R. ccBrulea. 
Agreeing generally with members of the genus Prion, Pseudoprion, and Hetero- 
prion, but differing in its square tail and thin bill ; the latter agrees best with 
thin-billed members of Heteroprion, but the strong nail immediately separates it. 
The general facies recalls Pterodro^na. In the Monograph, Classification, p. xlix., 
it is stated that the first and second primaries are subequal while in Prion 
the first primary is longest. This is copied from the Catalogue of Birds, but in the 
British Museum there were only three specimens, one a juvenile, the second 
just completing its moult, and the third the type of P. forsteri Smith ; this 
last-named has the first primary the longest, and all the other specimens I have 
seen also have the first primary longest, so that I conclude that fully-grown 
examples have always this feature. 
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