20 EINAR LONNBERG 
In Cat. Birds B. M. Vol. XIV, p. 100, SAUNDERS puts the length of the 
wing of Sterna lunata to 10,5 in. or, about 263 mm. REICHENOwW in his hand- 
book »Die Végel» records the same measurement as varying between 240 and 
270 mm. It is thus a remarkably great length of wing in these birds, and it 
may indicate a greater race in the eastern parts of the Pacific, but I have not 
material enough to solve this problem. 
Mr. BACKSTROM gives the native name as Manutara. Now, this is the 
holy bird of the islanders and figured in the famous bird cult. Mrs. ROUTLEDGE 
(The mystery of Easter Island, London 1919), however, indicates the »sooty 
tern» as the Manutara, and the Sooty Tern must correspond to Azous and not 
to Sterna lunata. 
Anous stolidus unicolor Nordmann 
Native name: Tuau (according to Mr. BACKSTROM). 
Motu Nui: 1 ¢ ad.,1 ¢ juv., 1 2 78/6 1917. 
The young male has not yet acquired the white cap, and the young 
female is just in moult with mixed white and brown feathers on the crown. 
The length of the wing of the adult male is 283 mm. From a geograph- 
ical point of view this Noddy ought to be referred to unicolor, and its size 
also speaks in favour of such a view, but the material does not allow further 
discussion of the question. 
This species nested in grass-covered places. 
Procelsterna caerulea skottsbergii n. subsp. 
Native name: Tubi. 
Hanga Piko: 2 go 78/6 1917. 
Motu Nui: 2 22 78/6. 1917. 
Length of wing in males 1I95—196,5 mm. 
» 5 oe, » females 193—194,5 » 
» » culmen » males 26—27 mm. 
» > » » females 27,5 mm. 
» >» tarsus » males 26 mm. 
» mbes » females 24,5 mm. 
These birds are all very pale with breasts, belly and under wing-coverts 
pure white, crown and fore-neck very nearly so, while the sides of the head 
(the small semilunar black spot in front of the eye is present) and the upper 
neck display the palest shade of bluish ash. This darkens gradually on the 
mantle, back, rump and tail. The secondaries are also ash grey with white 
tips, but the primaries darker, more slaty, with blackish shafts and more or 
less pale on the inner web. The under tail-coverts are white only with a 
light ashy shade on the tips of the longest ones. 
