ORCAS(Ὀρκάς, Ptol. 2.3.1), a promontory on the N. coast of Britannia Barbara, now Dunnet Head. It should be remarked, however, that Ptolemy (l. c.) places it on the E. coast, and gives it the additional name of Tarvedum (Ταρουιδούμ).[T.H.D]