104 A MANUAL OF THE BIRDS OF AUSTRALIA. 



Procelsterna albivitta Bonaparte, Comptes Rendua Acad. Sci. Paris, VoL XLII., p. 773, May 

 1856. New name for A. cinereus Gould. 



ProceUterna cerulea kermadeci Mathews, Austral Av. Rec., Vol. III., pt. 3, p. 55, April 7th, 

 1916 : Kermadec Islands. 



DISTRIBUTION. Probably as a straggler to east coast of Australia. 



Adult male. General colour above ash-grey, paler and inclining to white on 

 the head, sides of face and entire under -surface of body, including the under wing- 

 coverts ; under tail-coverts ash-grey like the upper -surface ; inner webs of outer 

 primary-quills inclining to black near the shaft, the innermost portion becoming 

 whitish ; most of the secondaries grey margined with white at the tips ; short 

 feathers encircling the eye, black in front and white on the hinder portion ; bill 

 black ; iris blackish-blue ; tarsi and toes black, webs lemon-yellow. Total length 

 279 mm. ; culmen 29, wing 207, tail 120, tarsus 24. 



Adult female. Similar to the adult male but smaller. 



Immature. Differs from the adult in being dark slate-grey both above *nd 

 below, the wings being somewhat darker than the back and the primary -quills 

 inclining to black. 



Nestling. Almost the same colour as the parent bird. 



Nest. None ; the eggs are laid on the bare rock or sand. 



Egg. Clutch, one ; ground-colour stone, with underlying spots of grey sparingly 

 distributed, and fewer spots of chestnut-brown ; axis 42 mm., diameter 30. 



Breeding -season. September to January. (Norfolk Island.) 



Distribution and forms. Apparently Pacific Ocean only where, however, five 

 forms have been distinguished, as follows : P. c. cerulea (Bennett) from Christmas 

 Island and Hawaiian Group ; P. c. teretirostris (Lafresnaye) from the Paumotus, 

 Marquesas and Society Groups ; P. c. nebouxi Mathews, from the Ellice and Phoenix 

 Groups darker and smaller than preceding which are all darker than the next two ; 

 P. c. cinerea (Gould) from Norfolk, Lord Howe, Kermadec Islands, probably Friendly 

 Islands, much paler above and below and also larger ; the form P. c. imitalri.r 

 Mathews, from St. Ambrose Group of the coast of South America, agreeing almost 

 exactly in coloration but a little larger. 



Genus LEUCANOUS. 



Leucanous Mathews, Birds Austr., Vol. II., pt. 4, p. 432, Nov. 1st, 1912. Type (by original 



designation) : Gygis microrhyncha Saunders. 



Gygis Wagler, Isis, 1832, heft 11, col. 1223, Nov. Type (by monotypy) : Sterna Candida 



Gmelin. 



Not Gyges Bory de St. Vincent, Ency. Meth., p. 449, 1825. 



Alphagygis Mathews, Austral Av. Rec., Vol. II., pt. 5, p. 110, Sept. 24th, 1914. New name 



for Gygis Wagler 1832, as above. 



Small Noddies with long stout bills, long wings, medium tails and very short 

 legs, and long toes with indented webs. The diagnostic characters of the genus 

 are the shape of the bill and the very short legs, and long toes with deeply indented 

 webs. The bill is longer than the head with the culmen straight or even slightly 

 upturned, while.it is very deep at the base proportionately. The tail is less than 

 half the length of the wing and the outer rectrix is shorter than the second which 

 is longest. The middle toe is almost twice as long as the metatarsus though not 

 much more than half the culmen. 



The bird described as Gygis microrhyncha by Saunders differs from the above 

 in having a long slender bill and a proportionately shorter tail of different formation, 

 the third rectrix from the outside being the longest, while the first is absolutely 

 shortest. In Sterna alba Sparrman the outside rectrix is longer than the two centre 

 pairs, the centre feather being the shortest. 



Coloration all white. 



