212 LARID.II. 
old H. hyhrida, which Tern, when flying in the bright sunshine 
and showing the blackish belly, is very apt to be mistaken for 
the present species. 
The White-winged Black Tern in the adult plumage has the 
head, neck, and underparts all black, the vent, tail, and tail- 
coverts pure white. 
Total length 8 to 95 inches. 
306. Hydrocjhelidon FissiPES (Linn.). The Black Tern. 
" This Tern is abundant near Tangier when on passage, 
crossing the Straits in large flights during May, and return- 
ing in September and October. They are not seen in the 
winter months.^' — Favier. 
The Black Tern, on the Spanish side, begins to appear about 
the end of April, and is rather later than H. hyhrida, nesting 
also later in the same situations as that species, but not in 
such numbers. I have noticed quantities crossing the Straits 
on the 16th of May. They are often seen on arrival, hawking 
about over cornfields and low ground near water. 
This Tern is more lead-coloured than black, having the tail 
slaty grey. 
Total length about 10 inches. 
*&' 
Subfam. LarintE. 
307. RissA TRiDACTYLA (Linn.\ The Kittiwake. 
" This species is nearly as common during winter in the 
Straits as the Herring-Gull, appearing during the month of 
November and leaving in March.^' — Favier. 
The Kittiwake is to be seen at times in great abundance 
during winter in the Bay of Gibraltar ; at other times hardly 
any are to be found : their presence or absence is due to 
the state of the weather. 
308. Larus gelastes, Licht. The Slender-billed Gull. 
Spanish (for all Gulls). Gaviota. 
Favier only records a single specimen of this Gull as ob- 
tained by him near Tangier, in 1852; but he remarks that the 
