NOTES ON BIRDS FROM EASTER ISLAND 2) 
This latter characteristic is especially noteworthy, because MATHEWS 
(Birds of Australia, Vol. 2, p. 426) says about P. caerulea cinerea (with a 
distribution from Northeastern Australia to the Kermadec Islands): »under tail- 
coverts ash-grey like the upper surface». This latter characteristic together 
with the great length of its wings (207 mm. according to MATHEWS) makes 
P. ¢. cinerea easily distinct from the Easter Island birds. 
Another of the light-coloured Pvrocelsternas has been named P. cacrulea 
imitatrix by MATHEWS. It is from San Ambrosio Island off the coast of Chile, 
thus geographically not so very far distant from Easter Island. It is, however, 
much larger (culmen 30,5, wing 215, tarsus 28 mm.) and thus easily distingu- 
ished from the present form. 
The remaining three subspecies of Procelsterna differ strongly from the 
Easter Island bird by their much darker colour. Thus P. c. caerulea from 
Christmas Island, Hawaiian group, is grey on the crown and the under parts 
of the body; P. c. teretirostris Lafresnaye is »subtus tota cinerea» and »supra 
brunnescenti-schistacea alis caudaque nigro-schistaceis, capite colloque cinereis», 
&ca. It is from the Paumotu, Marquesas and Society groups (fide MATHEWS). 
The third dark subspecies MATHEWS named P. c. xebouxz; it is from the Ellice, 
Phoenix and Samoa groups, and has »grey inner wing-coverts», and is said to 
be »obviously darker than éeretirostris and caerulea». 
It is thus evident that the Easter Island bird has developed into a separate 
geographical subspecies, which I take the pleasure of naming for the director 
of the expedition. 
According to Mr. BACKSTROM this species nested on the main island 
(Rano Raraku) as well as on Motu Nui. In the former place the eggs were 
laid on the bare rock, in the latter among grass about 15 cm. high. 
Gygis alba royana Mathews 
Native name: Quia-Quia. 
Rano Raraku: 1 gd, 1 2 ®%e 1917. 
These two birds have blackish shafts to the quills and the distance 
between the feathering of the forehead and the nostril about twice as large as 
the length of the nostril. 
Length of wing 245 mm. in male, 244 in female. 
» » culmen AZ .» » Io eA Ore » 
In these dry specimens the web is yellow (rather pale), but the toes and 
tarsi dark; it is possible that the latter have been greenish or bluish during 
life. The length of the tarsi is about 13 mm. 
In his great work »The birds of Australia» MATHEWS discusses the dif- 
ferent forms of Gygis and expresses the opinion that the type of SPARRMAN’S 
»Sterna alba» was from the Atlantic. This view he bases on SPARRMAN’S 
figure to this name in »Museum Carlsonianum», which displays white shafts to 
the quills. Fortunately SPARRMAN’s type specimen is still kept in this museum, 
