462 Hollister, Ring-necked Duck. [o"t. 



with this persistence of the reddish mark on the neck of the male 

 collaris it is interesting to note that the brown ring is completely 

 hidden in life when the Duck is in repose. In the National Zoologi- 

 cal Park, where the birds may be watched at close range, it often 

 requires continuous observation of a swimming male Ring-neck for 

 a considerable period to get a glimpse of the collar, which is seen 

 then only when the head is extended. 



The elimination of collaris from the typical subgenus Marila 

 would naturally bring up the question of the dismemberment of 

 Marila into two or more genera, a problem which experienced 

 ornithologists have attempted without happy results, or after long 

 study have given up as impossible. Groups approximately equiva- 

 lent to the Nyroca and Marila of the ' Check-List ' have been recog- 

 nized as genera by many authors, and recently the division of 

 Marila into three full genera, Nyroca, Marila, and Aristonetta, 

 has been advocated. 1 In effect of course this does nothing more 

 than to raise the three subgenera of Marila, as recognized in the 

 A. O. U. ' Check-List,' to the rank of genera. The Ducks of this 

 group seem to me, considering all the known forms, so intimately 

 blended as hardly to justify even subgeneric division. I am well 

 aware that numerous " characters " may be found to divide them into 

 groups, even to making several full genera; but such distinctions 

 will always be a matter of personal opinion, and sometimes do not 

 show sufficient concern for the apparent derivations of the forms. 

 The genus Marila in an unrestricted sense is a fine example of a 

 cosmopolitan, homogeneous group of birds, not large enough to be 

 unwieldly — and why split it up? To be really consistent in such 

 a division of Marila as has been suggested, the Redheads would 

 have to be separated from Nyroca, as the type of this subgenus 

 (Marila nyroca) differs as much in many features, and particularly 

 in the form of the bill, from our Redhead and from Marila ferina 

 (the type of Aythya Boie, 1822) as all do from the type species of 

 the subgenus Marila (M. marila), which in turn differs very appre- 

 ciably in the form of the bill from Marila affinis, the Lesser Scaup. 

 As for "Aristonetta," I think that the European Pochard (Marila 

 ferina) presents almost as perfect an intermediate, in the form and 



> Oberholser, Proc. Biol. Soc. Washington, vol. 31, p. 98. June 29, 1918. 



