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 Ouzel 的独立歌曲非常难以描述，因它们如变，同时又如融合。

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.

后一种鸟的上颌骨薄片比普通鸭粗糙得，汇合在一起， 每侧约有 27 个， 向上终止于牙齿状的突起。