On one occasion we had an excellent opportunity of watching a small <e1>covey</e1> of willow <e2>grouse</e2>, almost as pure white as the snow upon which they were running.
On one occasion we
On one occasion we had an excellent opportunity of watching a small covey of willow grouse, almost as pure white as the snow upon which they were running.
<triplet> covey <subject> grouse <object> Member-Collection(e2,e1)