The Latinised form of the name. Cf, Frisian Stirn, German Tanner, Swedish Fisk-tarna, Norwegian Makrel-tern, our Tern or Tarney. Derivation unknown.
Bill slender, lengthened. Tail much forked, with outer rectrices prolonged and generally more than half length of wing (S. anglica less than half, S. seena more than three-quarters). Webs well developed.
Crown black in summer.
Wing from 11 1/4" to 15".