72 A MANUAL OF THE BIRDS OF AUSTRALIA. 
Genus SULA. 
Sula Brisson, Ornith., Vol. I., p. 60, Vol. VI., p. 494, 1760. Type (by tautonymy): Sula = 
Sula leucogaster Linné. 
Dysporus Iliger, Prodr. Mamm. et Av., p. 279, (pref. April) 1811. Newname for Sula Brisson. 
Sularius Rafinesque, Analyse de la Nature, p. 72, 1815. New name for ‘“‘ Sula Lac.” = Sula 
Brisson, c/. Auk, Vol. XXVI., p. 50, Jan. 1909. 
Abeliera Heine und Reichenow, Nomencl. Mus. Hein., p. 351. (pref. Sept.) 1890. Newmname 
for ‘Sula Reichb. 1853’ = Sula Brisson. 
Hemisula Mathews, Austral Av. Rec., Vol. II., pts. 2 and 3, p. 55, Oct. 23rd, 1913. Type 
(by original designation): Sula leucogaster rogersi Mathews. 
Small Suline birds of dark coloration above, with general characterr as in 
Piscatrix, but with different proportions. 
The bill is a little longer, but the tail is much shorter, while the metatarsus 
and toes are notably long. The bill is typically Suline, more than half the length 
of the tail, but less than twice the metatarsus. The wing is long, more than twice 
the length of the tail. The metatarsus is coarsely reticulate with small scales, the 
scales being smaller on the hinder aspect. The toes have the posterior joints clearly 
reticulate, the anterior ones covered with scutes more or less broken up. This 
genus is defined by the coloration of the adult, a character differentiating it at 
once from the rest of the Suline birds. 
The immature plumage of this bird and Piscatrix show great similarity, while 
the adults show just as great a dissimilarity. The evolution of Piscatrix from its 
immature whole brown plumage passes through the stage when the brown is lost 
on the belly first. The present genus seems to show a peculiar stoppage in this 
course, this bird showing a brown coloration throughout, save the breast and 
abdomen, which are pure white. Though practically the same wing length is 
developed, the tail in Piscatrix has grown much lorger, the metatarsus lengthening 
in Sula. 
53. Sula leucogaster.—BROWN GANNET (BOOBY). 
[ Pelecanus leucogaster Boddaert, Tabl. Planch. Enlum., p. 57, (pref. Dec. Ist) 1783: Cayenne. 
Extra-limital. } 
Gould, Vol. VII., pl. 78 (pt. xxnt.), June Ist, 1846. Mathews, Vol. IV., pt. 3, pl. 228, June 
23rd, 1915. 
Pelecanus plotus Forster, Descr. Anim., ed. Licht., p. 278, (pref. Jan. 1st) 1844: near New 
Caledonia. 
Sula leucogaster rogerst Mathews, Austral Av. Rec., Vol. I., p. 189, March 20th, 1913: Bedout 
Island, mid-West Australia. 
DiIsTRIBUTION.—Tropical Northern Australia. 
Adult male—Entire upper-parts, throat, fore-neck, and sides of breast chocolate- 
brown, somewhat darker and more blackish on the primary-quilJs ; secondaries 
white at the base of the inner webs ; under wing-coverts chocolate-brown, except 
the median series which are white ; breast, abdomen, sides of body, axillaries, and 
under tail-coverts pure white. Bill and skin yellow, spot in front of the eye blue ; 
iris silver-grey ; feet pale yellow. Total length 710 mm.; culmen 84, wing 374, 
tail 200, tarsus 43. 
Adult female—Similar to the adult male but larger. 
Immature and young.—Described by Dr. Macgillivray: The young birds are 
hatched with eyes closed, with only an indication of down on head, back, humeral, 
femoral, and each pectoral region. The eyes open very soon, and the birds become 
covered with whitish down at an early stage, the beak and legs being of a pale slaty- 
grey, much the same colour as the naked skin ; the gape also a pale slate colour. 
They grow almost to full size before acquiring any feathers, the first to appear being 
