RHODOSTETHIA.
Tail bill small, shorter than head.
Rhoclostethia rosea (Macgillivray). Ross's GULL.
j 9 summer. Above pale grey, tail white ; head and under parts white with bright rosy tinge, collar and outer web ist primary black. Bill black. vermilion. Legs and feet red. In winter, there is no black collar, and top of head is greyish. Wing 26o-266. Tarsus 3o-32. Bill 13-59 (H.). Young :
white ; spot behind ear, shoulders, inner wing coverts, tips of primaries and end of tail brown ; legs and feet brown.
Ifreeds.—Only known locality so far is in N. Siberia (Kolyma Delta). Has occurred all over Arctic regions ; is a rare winter visitor to Europe, recorded Faroes, I leligoland, Yorkshire, France and Sardinia.