The cceca coll are voluminous, and have twelve continuous longitudinal folds in their mucous membrane.

The pterylosis differs somewhat from that of the pigeon.

The lateral neck-spaces reach only to the beginning of the neck ; the superior wing-space is absent ; the lumbar tracts coalesce with the posterior part of the dorsal tract, and the latter joins the plumage of the tibia.

The sand-grouse possess an after-shaft on the contour feathers, thus differing from the pigeons, and, unlike the Gallinaceous birds, have a naked oil-gland.

In some characters these birds are plover-like, but they drink like a pigeon, thrusting the bill up to the nostril into the water, and retaining it there until the thirst is satisfied.