\Si`pho*no*bran`chi*a"ta\, n. pl. [NL. See
{Siphon}, and {Branchia}.] (Zo["o]l.)
A tribe of gastropods having the mantle border, on one or
both sides, prolonged in the form of a spout through which
water enters the gill cavity. The shell itself is not always
siphonostomatous in this group.