Vol. 30, pp. 119-120 May 23, 1917 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 





DESCRIPTION OF A NEW GENUS OF ANATIDAE. 

 BY HARRY C. OBERHOLSER. 



The Laysan teal, Anas laysanensis, is a bird of considerable 

 interest by reason of its rarity and its limited island distribu- 

 tion. It was originally described from the island of Laysan by 

 Dr. Walter Rothschild in 1892;* and since then but few speci- 

 mens have been obtained, and comparatively little concerning 

 its life history has been made known. 



This species has been commonly placed in the genus Anas 

 Linnaeus, but recent examination of the specimens in the 

 United States National Museum, including the Biological Survey 

 collection, shows that it certainly does not belong in that group. 

 As it is not referable to any other known genus, it becomes 

 necessary to provide a new monotypic generic group for its re- 

 ception, as follows : 



Horizonetta, gen. nov.t 



Chars, gen. — Similar to Anas Linnaeus, but bill more spatulate, decid- 

 edly wider terminally than at base, more depressed and slightly upturned ; 

 basal portion of culmen more elevated, narrower and more sharply 

 ridged; nail of maxilla more triangular; lamellae of maxilla and mandi- 

 ble much less well developed, in places even obsolescent; and tertials 

 relatively longer. 



Type. — Anas laysanensis Rothschild. 



Remarks. — Excepting Anas Linnaeus, the nearest ally of this peculiar 

 genus is apparently Querquedula Stephens. From Querquedula it differs 

 in having the bill much shorter, relatively broader, and somewhat more 

 depressed, the lamellae on both maxilla and mandible very much shorter 

 and less prominent, in some places almost obsolete; tertials longer and 

 broader; tail double-rounded, the central pair of rectrices shorter than 

 the adjoining pairs; middle toe without claw longer instead of shorter 



• Anas laysanensis, Bulletin Brit. Ornith. Club, I, December 31, 1892, p. xvii (island 

 of Laysan, Hawaiian Islands). 



t From opt'jw, limito; j/^TTo.anas. 



28— Proc. Biol. Soc. Wash., Vol. 30, 1917. (119) 



