98 A MANUAL OF THE BIRDS OF AUSTRALIA. 



Adult in winter-plumage. Similar to the adult in breeding-plumage, but lores 

 and the crown of the head mottled with white. 



Immature male. Wings dark brown ; entire back ash-brown, the feathers 

 edged with white ; upper tail-coverts paler with no white edges ; middle tail-feathers 

 similar, slightly fringed with white on the inner webs, outermost pair of feathers 

 white at the base and fringed with white at the tip on the outer webs ; fore-head and 

 lores white, the latter with a few dark dots which indicate the black of the adult ; 

 head black with white margins to the feathers, which imparts a streaked appearance ; 

 hind-neck very pale grey ; entire under-surface pure white. 



Immature (first plumage). Uniform brown above, the scapulars, secondaries and 

 upper wing-coverts buff tipped ; sometimes the whole of the feathers of the upper 

 back have bright buff tips ; sometimes the tips are almost absent ; the feathers of 

 the top of the head have white tips, the eye-stripe being indicated by a lighter streak, 

 the loral patch being darker ; the back of the neck darker than the head or back, 

 and the under-surface white with a dirty grey wash varying in intensity. 



Nestling. Brownish all over above, the down with a mixture of white, obsolete 

 darker patches being indistinctly seen ; throat and chest as back ; abdomen dirty 

 white. With age the down appears lighter and the first feathers show with rufous 

 tips. 



Nest. A fissure of a rock close to the water's edge, without any nest, or well 

 concealed under a tussock of grass. 



Egg. Clutch, one ; ground-colour stone, spotted all over with rich chestnut, 

 and smaller spots of grey ; axis 44 mm., diameter 31-32. 



Breeding-season. October to December. 



Distribution and forms. Throughout the tropical seas of the world, breeding 

 on isolated islets. Mathews separated five forms and two have since been added, 

 thus : M. a. ancethetu* (Scopoli) from the Philippine Islands and the China Sea ; 

 M. a. novcehollandice (Stephens) from East Australia, separable by its greyer neck, 

 darker brown upper coloration, larger size and different tail coloration ; the West 

 Australian M . a. rogersi Mathews is similar but much darker ; M . a. antarctica (Lesson ) 

 from the Seychelles, Mauritius and Laccadives is a smaller race than the preceding, 

 which it resembles in coloration ; M . a. fuligula (Lichtenstein) from the Red Sea is 

 larger than above and has less white on inner web of the primaries and more white 

 on^the tail-feathers ; M. a. recognita Mathews, from East America, breeding on the 

 Bahamas, is generally lighter above, especially on the tail, and obsolete grey wash on 

 under-surface and different tail coloration ; and M . a. nelsoni (Ridgway) from Pacific 

 Coast of Mexico and Central America, larger than preceding with relatively longer or 

 more slender bill and under parts of body tinged with pale grey. 



Genus ONYCHOPRION. 



Onychoprion Wagler, Isis, 1832, heft 3, col. 277, March. Type (by monotypy) : Sterna 

 serrata Wagler = S. fuscata Linnet 



Planetis Wagler, Isis, 1832, heft 11, col. 1222, Nov. Type (by monotypy): S. guttata ex 

 Forster MS. = S. fuscata Linne. 



Haliplana Wagler, Isis, 1832, heft 11, col. 1224, Nov. Type (by monotypy) : Sterna fuliginosa 

 Gmelin = S. fuscata Linne. 



Thalassipora Riippell, Syst. Uebers. Vogel Nord-ost Afrika, p. 140, 1845. Type (by mono- 

 typy) : S. infuscata Lichtenstein = S. juscata Linne. 



Dipsaleon Gistel, Naturg. Thierr. Schul., p. 10, 1848 (pref. Easter 1847). New name for 

 Planetis Wagler. 



Medium-sized Terns with comparatively short stout bills, short legs, long 

 wings and very long tails. The culmen is a little longer than the head, and much 

 longer than the tarsus. The nature of the nostrils shows an approach to that seen 

 in the Noddies. The toes are comparatively short and fully webbed. The streamers 

 are well developed, making the tail more than half the length of the wing. 



