88 
their mandibles, as well as in the fringe-like pectinations of the base of 
the upper mandible; this latter character bemg much more prominent 
in the larger than in the smaller species of the group, in which, 
indeed, it is almost obsolete, if not entirely absent. I consider the 
members of this genus to constitute a very distinct group among the 
Petrels, quite equal in point of interest and value to that of the 
Thalassidrome. 1 have had many opportunities of observing the 
whole of them in their oceanic haunts, and did not fail to observe that 
every five or six degrees of latitude was frequented by a different and 
distinct species: they all inhabit the wide ocean, and rarely visit the 
land except for the purpose of incubation: they are often seen in 
immense flocks, and sometimes in multitudes: they never mount 
high in the air, but are altogether the most light, buoyant and fairy- 
like members of the great group to which they belong: their great 
stronghold is the temperate latitudes of the southern ocean, and 
until the occurrence of the present new species, I have never heard 
of one being found north of the equator. The species to which the 
Madeiran bird is most nearly allied, is that to which I have given 
the name of P. Ariel, and which I met with and shot in great 
numbers in Bass’s Straits. It differs, however, in being smaller in 
all its admeasurements, in having a shorter, more swollen or robust 
bill, particularly with reference to the nostrils and the terminal hook 
of the upper mandible. For this new species I propose the name of 
Prion srevirostris. (Pl. XCIII.) 
Upper surface delicate blue ; edge of the shoulder, the scapularies, 
outer margins of the external primaries and the tips of the middle 
tail-feathers black ; lores, sides of the head and all the under surface 
white, stained with blue on the flanks and under tail-coverts; bill 
light blue, deepening into black on the sides of the nostrils and at 
the tip, and with a black line along the side of the under mandible ; 
feet light blue, the interdigital membrane flesh-colour. 
Total length, 103 inches; bill, +3; wing, 64; tail, 33; tarsi, 13. 
3. DESCRIPTIONS OF SOME NEW SPECIES OF ANT-THRUSHES 
(Formicartin2£) From Santa FE pi Bogota. 
By Painie Luruey Scuater, M.A., F.Z.S. 
(Aves, Pl. XCIV.—XCVII.) 
1. GRALLARIA HYPOLEUCA. 
G. supra ferruginea, loris albidis: subtus alba, lateribus magis 
cinerascentibus : tibiis et hypochondriis brunnescentibus. 
Long. tota 6°5, alee 3°5, caudee 1°8. 
The collection of the Jardin des Plantes at Paris contains the only 
example I have yet seen of this bird, which appears to have escaped 
the notice of the French ornithologists. It is marked as having 
been received from Bogota in 1843 by M. Rieffer. Its form is typi- 
cal, but in colouring it differs from all hitherto known members of 
the genus, though perhaps showing some resemblance to Grallaria 
