352 BIRDS OP NORFOLK. 



shore of the Wash, and from that time they were found 

 in parties all round the coast of Norfolk, and in many 

 inland localities, the bulk remaining till the end of the 

 month. At Yarmouth Mr. Stevenson was informed that 

 stragglers were seen even later. 



From a careful estimate Mr. Stevenson was of opinion 

 that not less than two hundred skuas, mainly of this 

 species, were killed in the county. As may be supposed, 

 the Norwich naturalists had excellent opportunities of 

 examining large series of these birds, of which they 

 availed themselves to the full ; and Mr. Stevenson gives 

 some valuable details of plumage and other peculiarities, 

 for which I must refer to the paper already so extensively 

 quoted, merely observing that many excellent examples 

 were present, ranging from very young birds to Hiose 

 which had fully reached maturity, and of both the light 

 and dark-breasted forms ; of thirty-four specimens ex- 

 amined sixteen were adult, and six supposed immature 

 examples of the white-breasted form; two fully adult, and 

 six immature birds, probably of the black-breasted form ; 

 four others being immature and doubtful. " These four 

 young birds," Mr. Stevenson says, " I can only suppose 

 to be the result of ' mixed marriages,' such as Mr. 

 Saunders refers to in the case of the light and dark 

 forms of Eichard son's skua, and are about calculated 

 to drive an ornithologist wild. The more or less adult 

 birds, light or dark, were as eighteen to sixteen young 

 ones." 



A marked peculiarity in the plumage of the adult 

 birds is the form of the middle tail-feathers ; this was 

 pointed out by Professor Newton (" Proc. Zoological 

 Society," 1861, p. 402), who says " the middle tail- 

 feathers have a kind of tivist in their shafts, which brings 

 the lower surfaces to meet together towards their ex- 

 tremities in a vertical direction, and this peculiarity 

 gives the bird, when on the wing, a very peculiar appear- 

 ance." There seems to be no appreciable difference in 

 size, nor any satisfactory means of identifying the sexes 

 short of dissection, and Mr. Stevenson adds that the 

 reliable signs of maturity are — 



I . The under tail coverts being a pure sooty black, 

 and the upper of course without bars. 



