Two lumens , which are respectively efferent branchial vessel above and afferent branchial vessel below are arranged in reverse side of gill .
鳃的背方上下排列的2个管腔分别为出鳃血管和入鳃血管，腹方为结缔组织膜形成的鳃轴；
efferent branchial vesselefferent branchial vesselefferent branchial vessel