260 PHILOSOPHY OF ZOOLOGY. 



Base of the bill enlarged. 



201. OIDEMIA *. Scoter. Bill swollen at the base, 

 above the nostrils. Anas nigra audfusca. 



202. SOMATERIA. (Leach). Eider. Base of the bill 

 extending up the forehead, and divided by a triangular 

 projection of feathers. Anas mollissima and spectabilis. 



Base of the bill plain. 



203. CLANGULA. Bill short and narrow. A. glacialis y 

 histrionica and clangula. 



204. NYROCA. Bill broad and depressed. Anasferina, 

 nyroca, fuligida. 



2. Hind toe without a border. 



A papillous skin at the base of the bill. 



205. CAIHINA. Musk-duck. Face and cheeks with 

 a coloured warty skin. Anas moschata. 



Base of the bill feathered. 



206. TADOIINA. Shielddrake. Bill broad at the end, 

 hollow in the middle, and raised into a tubercle at the base. 

 A. Tadorna. 



207. ANAS. Bill plane above the nostril, and depres- 

 sed. A. boschas, clypcata, strepera, acuta, querquedula, 

 penelope and crecca. 



b. Trachea of the male simple at the bronchial extremity. 

 This group includes those species usually denominated 

 Swans and Geese. 



208. CYGNUS. Swan. Bill of nearly the same breadth 

 throughout. Anas Olor and Cygnus. 



209- ANSEII. Bill tapering. Anser, segetum, albl- 

 ?, Erythropus, Bernicla, and rfificollis. 



tumor. 



