What may be regarded as the separate songs of the Ouzel are exceedingly difficult of description, because they are so variable and at the same time so confluent.

可以被视为 Ouzel 的独立歌曲非常难以描述，因为它们如，时又如融合。

In this latter bird the lamellae of the upper mandible are much coarser than in the common duck, almost confluent, about twenty-seven in number on each side, and terminating upward in teeth-like knobs.

后一鸟的上颌骨薄片比普通鸭粗糙得，几乎汇合在一， 每侧约有 27 个， 向上终止于牙齿状的突。