DOVE PRION. 41 
collections. Forms ill defined; three have been named: H. c. caerulea (Gmelin) 
probably Kerguelen Land breeding bird ; H. c. victoria Mathews from Victoria as 
being smaller; Brooks has named as a species Halobena murphyi from South Georgia 
as having the bill much smaller, less slender and wider at the base; wing 212, 
tarsus 31, bill 25 mm. 
Genus HETEROPRION. 
Heteroprion Mathews, Birds Austr., Vol. II., pt. 2, p. 222, July 31st, 1912. Type (by original 
designation): Heteroprion belcheri Mathews. 
Small Petrels agreeing in general characters with species of the genus Pachyptila, 
but differing in the shape of the bill ; whereas in that genus the lateral plates are 
widely horizontally developed, and the under mandible rami enclose a broad 
distensible sac, in this the lateral plates are not abnormally laterally extended, and 
the rami of the under mandible are normal and no sac is present, the interramal 
space being narrow and feathered. The general nature of the bill is, however, 
similar, the nasal tubes being short, the nail weak and small, and the space between 
the nasal tubes and the nail longer than the former. 
31. Heteroprion belcheri.i—THIN-BILLED PRION. 
Mathews, Birds Austr., Vol. II., pt. 2, figs. in text, p. 215, July 31st, 1912. 
Heteroprion belcheri Mathews, Birds Austr., Vol. II., pt. 2, p. 224, figs. in text, p. 215, July 
3lst, 1912: Geelong, Victoria. 
DisTRIBUTION.—Southern Australian Seas. 
Adult—Like the H. desolatus group in general coloration, but easily separated 
by its very thin bill, whose width is less than a third of its length; bill blue with 
yellow tip, nasal tube black. Feet blue with yellow webs. Wing 183 mm.; culmen 
(exp.) 25 mm. long, 8 wide at base, tarsus 33. 
Immature, Nestling, Nest and Eggs—Unknown. 
Distribution and forms.—Since this species was differentiated as above, we have 
seen single specimens from New Zealand, West Australia and the Falkland Islands, 
indicating a Sub-antarctic Circle range. The Neozelanic form, has a longer, slightly 
wider bill, and a series from the Cottesloe Beach, West Australia, show young birds 
with a bill 24 mm. long by 8.5 broad, and adult male and female with bills 25 mm. 
long by 10 mm. wide ; an immature and adult from the Falkland Islands have bills 
23 by 8 mm. and 25 by 10 mm. respectively. 
32. Heteroprion desolatus.—DOVE PRION. 
[Procellaria desolata Gmelin, Syst. Nat., Vol. I., pt. u., p. 562, April 20th, 1789: Kerguelen 
Island. Extra-limital.] 
Mathews, Birds Austr., Vol. II., pt. 2, figs. in text, p. 231, July 31st, 1912. 
Heteroprion desolatus mattingleyi Mathews, Birds Austr., Vol. II., pt. 2, p. 226, July 31st, 
1912: Geelong, Victoria. 
DistTRIBUTION.—Southern Australian Seas. 
Adult male—Blue-grey above, including the head, hind-neck, back, wings, 
and tail; the head and rump darker than the back ; lesser wing-coverts and long 
scapulars blackish, as also the tips of the middle tail-feathers ; bastard-wing and 
primary-coverts black, the latter narrowly margined with white at the ends; the 
four outer primaries black, inclining to white on the inner webs ; inner primaries 
and secondaries grey, with more or less white on the inner webs ; lores, cheeks, a 
line over the eye and under-surface pure white (no blue wash on flanks) including 
