472 THE LACCADIVES AND THE WEST COAST. 
S. Bergii Wing. Billat F. Tarsus. Locality. 
” g$ 143 2""55 1-22 Mergui, Tenasserim. 
Reasearch "35 VM, i 
7m S$ 143 2" 58 1’-25 Bopyin, souht of Mergui. 
T observe that Messrs. Finsch and Hartlaub (Central Poly- 
nesia, p. 216) and Baron Heuglin (Nord. Ost., Africka, p. 1436) 
unite with the present species, Sterna pelecanoides, King, and 
poliocercus, Gould. I am much disposed to believe that in 
this they are in error, and that Professor Schlegel, who sepa- 
rates these two, is correct. 
I have, from the Society Islands, a Tern, which I consider 
to be Sterna pelecanoides. Its dimensions are as follows :—Wing, 
12:7; bill at front, 2°05; tarsus, 1-1. It will be seen how 
these dimensions contrast with those above given of twenty- 
three specimens of Bergit. 
Besides this difference in size, the colour of the upper parts 
is markedly paler than in 19 out of 20 Bergii, and is somewhat 
paler than even the most exceptionally pale Bergit. 
As for poliocercus, Gould, I cannot see how any doubt as to its 
distinctness can arise; a peculiarly fine male in full breeding 
lumage from Port Lincoln, South Australia, measures—wing, 
13-3; bill at front, 2°27; tarsus, 1-0. 
By the comparatively small tarsus, by the much slenderer 
and more compressed bill, by the uniformly pale tint of the 
tail with the whole of the outer tail feather white, except only 
a little grey powdering on the inner web just at the tip, polto- 
cercus appears to me to be clearly distinguished from both 
Bergit and pelecanoides, 
I take this opportunity of noting my inability to comprehend 
how Messrs. Finsch and Hartlaub consider it correct to unite 
Sterna longipennis of Nordmann (which I may mention occurs 
upon our Indian coasts) with Sterna frontalis, Gray. 
The true longipennis as 1 understand the species is very close 
to the Arctic Tern, Sterna hirundo, but has a slightly longer 
wing, a slightly stronger bill, which is black at all ages, anda 
tarsus intermediate in length between that of S. hirundo, the 
Arctic Tern, and 8. fluviatilis, the common Tern.* 
ie As to the differences between these two species Mr, Dresser remarks :—[ Birds 
of Europe :-— 
“3 The adults of these two birds are not difficult to recognize when in full plum- 
age, and the present species (fluviatilis) may always be known—(1) by the black 
marking on the bill near the tip; (2), by the stronger foot and longer tarsus, 
measuring at least 0°7 inch ; and (3), by the wings reaching beyond the tail. In the . 
adult Aretic Tern the bill is entirely coral-red, the tarsus only measures 0°55, and 
the tail reaches beyond the wings ; hence the name of macroura, which it sometimes 
goes by. The young birds are rather more difficult to separate, but may be distin- 
guished by the fullowing characters:—viz., by the amount of black on the inner web 
