ART. 16. BIKDS FROM NORTH CELEBES RILEY. 55 



coverts, secondaries, and scattering feathers on the back and head 

 are tipped with a brighter violet ; the tail is washed with violet. It 

 is evidently an immature bird and is smaller than the other males. 

 The remaining males are probably adult and are of a shining dusky 

 dull bluish-green above ; the wings and tails with a steely-blue cast in 

 certain lights; the basal spot on the inner web of the outer tail 

 feathers is pure white. Two of the females in color are precisely 

 like the adult males, while two are like the immature male, except the 

 basal spot on the inner web of the outer tail feathers is more pro- 

 nounced, though reduced in size. This can hardly be due to imma- 

 turity as one taken at Besoa, October 31, has the outer tail feather 

 and tips of the primaries worn while the other is one of the birds 

 taken April 9. It may be that it takes more than a year to acquire 

 the fully adult plumage. The males average larger than the females. 

 The three adult males measure: Wing, 102-105 (103.5) ; tail, 37-43 

 (39.2) ; culmen, 3.5-4 (3.8). The four females measure: wing, 96.5- 

 101 (98.9) ; tail, 37.5-40 (39.1) ; culmen, 3-4 (3.5). The immature 

 male measures: wing, 94.5; tail, 37; culmen, 4. 



From the above it would appear that some of the very small 

 measurements accorded the wing by authors, along with normal 

 measurements in the various forms of this genus, was due to the in- 

 clusion of immature specimens, as in most of the races the only 

 way to tell the adults from birds of the year is by size. 



I have been unable to compare the above series with any other 

 specimens of the species. 



These probably nest in holes in the rock on the slopes of the crater (Kala- 

 bat).— H. C. R. 



116. COLLOCAUA VESTITA AENIGMA RUey.2 



Two males and three females, Parigi, September 10, 1916; one 

 male and two females, Gimpoe, August 1 and 29, 1917 ; one male and 

 two females, Pinedapa, February 13 and 21, 1918. 



The above series is very uniform in color. Four specimens of 

 Collocalia vestita vestita from Java before me are olivaceous black 

 No. 1 above; sooty hair brown below, the throats little lighter than 

 the breast, while in Collocalia vestita aenigma the back is a shining 

 black with little or no olivaceous sheen ; the lower parts smoke gray, 

 the chin and throat a silvery pale smoke gray or even whitish. The 

 upper surface of the wings and tail in Collocalia vestita aenigma 

 has a more deep dusky violet cast, not so olivaceous as in Collocalia 

 vestita vestita from Java. There is apparently no difference in 

 size. To Collocalia vestita meamsi of the Philippines, the Celebes 

 race is more closely related, but differs in being darker above, the 

 wings externally with a more dusky violet gloss; below it is lighter, 

 especially on the throat. The Celebes form is slightly larger. 



»Proc. Biol. Soc. Wash., vol. 31. 1918, p. 156 (Parigi, Celebes). 



