SYSTEMATIC ARRANGEMENT. 428 
XX. 
*-GULL. 
1. Black-backed, Gwylan gefn-ddu. 
2. Skua, Gwylan frech. 
3. Black-toed, Yr Wylan ysgafn. 
4, Arctic, Gwylan y Gogledd. 
5. Herring, Gwylan benwaig. 
Wagel, Gwylan ridd a gwyn. 
6. Common, Gwylan lwyd, Huc- 
can. 
Winter, Gwylan y gweunydd. 
7. Kittiwake. 
Tarrock, Gwylan gernyw. 
8. Black-headed, Yr wylan benddu. 
79. Red-legged. 
710. Laughing. 
11; Brown, — Yr wylan fechan. 
XXII. 
TERN. 
1. Common, Y for-wennol fwyaf. 
Yscraean. 
2. Lesser, Y fér-wennol leiaf. | 
