See 'Birds of Spain,' by Howard Saunders, Esq., published in the works of the Société Zoologique de France, where he says:—"C. ceruginosus et C. cyaneus ont les lisières extérieures des remiges émarginées, jusqu'à et y comprise la cinquième, et cette forme se trouve en presque toutes les Circus exotiques. En C. swainsonii (the Pallid Harrier) et C. cineraceus cette émargination successive se borne a la quatrieme." We have little to do with this distinction, except as between C. cyaneus and C. cineraceus, C. aeruginosus being otherwise sufficiently distinct, and C. swainsonii not coming within our limits.
"Tereus," I soon found, as I expected, was Mr. MacCulloch.
These reeds are the common reed Spires, Spire-reed, or Pool-reed. Arundo phragmites. See 'Popular Names of British Plants,' by Dr. Prior, p. 219.