- (dated, zoology) A taxonomic order within the class Gastopoda — marine gastropods in which the gills are developed on both sides of the body and the renal organs are also paired. The abalone (Haliotis) and the keyhole limpet (Fissurella) are examples..
- Zygobranchia in The Century Dictionary, The Century Co., New York, 1911
Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.