A cloud shadow passed over the skylights.

一道云影掠过天窗。

I wanted to preserve a few specimens of these delicate zoophytes, but they were merely clouds, shadows, illusions, melting and evaporating outside their native element.

我很想保留起这种精美植虫动物的一些品种，但它们不过是烟云、光影、空架，一离开原来的海水，就消敝得无影无踪。