Genus — P P I 0 N . 
Prion Lacepede, Tableau Oiseaux, p. 14, 1799 . . . . Type P. vittatus. 
PucAy^^^'Za Illiger, Prodromus, p. 274, 1811 .. .. .. Type P. vittatus. 
Priam'pTius Rafinesque, Analyse Nature, p. 72, 1815 . . Type P. vittatus. 
Small birds with a very broad bill, with short nasal tube ; the rami of the under 
mandible divergent and enclosing a distensible pouch which is unfeathered ; 
the nail of the upper mandible is small and weak, and separated from the short 
nasal tube by a long flattened space ; the lateral plates are extended and 
flattened so that they present a horizontal surface rather than a vertical one ; 
its breadth at the widest part more than half the length of the chord of the 
culmen ; as a matter of fact, very nearly two-thirds ; inside the upper 
mandible on each side is a row of comb-like lamellsB which extend the whole 
length of the lateral plates. 
The wing has the flrst primary the longest and the tail, consisting of twelve 
feathers, is long and wedge-shaped. The feet are of medium length, and slender. 
As restricted above the genus Prion will contain one species only, the 
well-known P. vittatus (Gmelin). The reasons which have led me to accept such 
restriction as being correct, will be fully dealt with in the following pages. 
In the Monograph of the Petrels, p. 285, is given the following resume of the 
genus Prion as there accepted : “Of the genus Prion four species are recognised. 
They are alike in plumage and markings. There is very little difference in the 
dimensions except in the bill, and in the development of the lamellae at the 
base of the upper mandible, but with respect to these characters great individual 
variation is displayed. Prion vittatus has the longest bill, its sides being dis- 
tinctly bowed and graduating towards the tip. P. hanJcsi has the bill bowed on 
the sides, but it is smaller. I have, however, examined some specimens which 
could not be referred with certainty either to P. vittatus or P. banksi, but were 
intermediate between the two. P. ariel and P. desolatus have the sides of the 
bill straighter, but as in the case of P. vittatus and P. banksi it is not\ always 
possible to separate the two species definitely. In 1879 Dr. Bowdler Sharpe 
gave a review of the genus Prion, and recognised four forms, which are dis- 
tinguished with difficulty. In 1896 Salvin admitted the same number of 
species, but relied principally on the presence or absence of lamellse in the 
biU, and in their more or less pronounced development. The same four species 
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