A collaris

Scaup Scaup (sk[add]p), n. [See {Scalp} a bed of oysters or mussels.] 1. A bed or stratum of shellfish; scalp. [Scot.] [1913 Webster]

2. (Zo["o]l.) A scaup duck. See below. [1913 Webster]

{Scaup duck} (Zo["o]l.), any one of several species of northern ducks of the genus {Aythya}, or {Fuligula}. The adult males are, in large part, black. The three North American species are: the greater scaup duck ({Aythya marila}, var. nearctica), called also {broadbill}, {bluebill}, {blackhead}, {flock duck}, {flocking fowl}, and {raft duck}; the lesser scaup duck ({A. affinis}), called also {little bluebill}, {river broadbill}, and {shuffler}; the tufted, or ring-necked, scaup duck ({A. collaris}), called also {black jack}, {ringneck}, {ringbill}, {ringbill shuffler}, etc. See Illust. of {Ring-necked duck}, under {Ring-necked}. The common European scaup, or mussel, duck ({A. marila}), closely resembles the American variety. [1913 Webster]