108 LAMELLIROSTRAL SWIMMERS — ANSERES. 



and then hiding in the grass, if there is any accessible. This bird is generally 

 regarded as being excellent eating, as its food consists chiefly of the roots and leaves 

 of plants found at the bottoms of ponds. 



In Southern Wisconsin — as Professor Kumlien informs me — this species is a 

 regular visitant in spring and in fall. It is not abundant, but is by no means rare. 

 A few of these birds — mostly those whose plumage is immature — remain all sum- 

 mer about Lake Koskonong — where, however, this species is not known to breed ; 

 but I am assured by Mr. Goss that it does this — in limited numbers — in the 

 neighborhood of Pewaukee. 



This Duck was found breeding near Fort Resolution by Mr. Kennicott in June. 

 It was taken in July, with its eggs, in the same neighborhood, by Mr. J. Lockhart ; 

 and also at Shoal Lake, in the summer of 1865, by Mr. Donald Gunn, who states 

 that he has sometimes seen as many as twenty eggs in a single nest. 



Eggs of this species from Guatemala and from Shoal Lake are in the Smithsonian 

 Collection. The latter (No. 12727) — collected by Mr. Gunn — are of a dull white, 

 with a slight shade of cream-color. They vary in their length from 2.35 to 2.55 inches, 

 and in their breadth from 1.80 to 1.85. The specimen from Duefias, obtained by Mr. 

 Salvin (No. 13434;, measures 2.55 by 1.85. 



Genus NOMONYX, Ridgwat. 



Erismatura, Auct. nee Boxatarte. 



Nomonyx, Ridgw. Proe. U. S. Nat. Mus. II. Mar. 27, 1880, p. 15 (type, Anas dominica, LinnJ. 



Char. Similar to Erismatura, but differing from all the species of that genus in the form of 

 tin- maxillary unguis, which is similar to that of Fulix and allied genera, the same being in Eris- 

 matura the most peculiar and important generic character. 



Altogether the most distinctive feature of the genus Erismatura consists in the remarkably 

 peculiar conformation of the maxillary unguis, or nail of the upper mandible. This, viewed from 



above, is extremely small, narrow, and linear, the broader terminal half being bent very abruptly 

 downward and backward, so as to be visible only from in front or below. With the sole excep- 

 tion of Anas dominica, Linn., all the species usually referred to this genus agree strictly witlr the 

 type, Anas leueocepluda, Scop., notwithstanding other characters are more or less variable. Anas 

 dominica, Linn., lias the nail of normal form, or very much like that prevailing among the Ducks 

 generally, and on this account should be separated geuerically from Erismatura. 



