110 Proceedings of Indiana Academy of Science. 
Perissonetta, gen. nov.’ 
Diagnosis—Similar to Nyroca, but length of exposed culmen equal to 
length of inner toe with claw (instead of decidedly shorter) ; feathering on 
sides of maxilla extending forward as far as the feathering at the base of 
the culmen; anterior outline of feathering at the base of culmen broadly 
convex ; and length of wing only about 4 times the length of exposed culmen. 
Description Wing 4 times the length of exposed culmen ; bill relatively 
little flattened terminally, its width near end about 11/8 times its width 
at base, its tip rounded, and its width at posterior end of nail about 2 times 
the length of the nail; tip of maxilla much hooked; nail of bill rather wide 
and subtriangular; height of bill at extreme base, 11/8 times its greatest 
width; base of culmen not deeply concave; exposed culmen about 21/4 
times the height of bill at extreme base, 22/5 times the greatest 
width of bill, and equal to the length of inner toe with claw; anterior out- 
line of feathering at base of culmen broadly conyex; the feathering on 
sides of maxilla reaching forward as far as that at the base of culmen; a 
short, bushy occipital and coronal crest. 
Type—Anas collaris Donovan. 
Remarks.—Mr. N. Hollister’s excellent article on this species’ serves but to 
emphasize the distinctness of this duck from its Old World relatives. As 
the characters that we have above given show, this species forms one of 
the most trenchantly distinct groups among the genera allied to Nyroca. 
Most of its distinctive characteristics are here for the first time presented, 
and it is quite evident that had they been appreciated before, the bird 
would long ago have figured as the type of a new genus, a fate that it seems 
to have escaped until now. In addition to the other characters by which it 
is readily and variously distinguishable from each of the generic groups here 
treated, it differs from all of these in the shape of the frontal feathering at 
the base of the culmen, and in the relative anterior extent of the feathering 
on the sides of the maxilla ; and also, from all but Avristonetta, in having the 
exposed culmen equal to the length of the inner toe with claw. Notwith- 
standing its coloration, it is fully as well differentiated from Fuligula as 
from Nyroca, as the following differences from the former show: wing only 
4 times the length of exposed culmen; height of bill at extreme base much 
more than the greatest width of bill; length of exposed culmen about 21/2 
times the greatest width of bill; exposed culmen equal to inner toe with 
claw; anterior outline of feathering at the base of culmen convex, that on 
sides of maxilla reaching as far forward as that at the base of culmen; 
occipital crest short. 
The only species assignable to this group must now be ealled Perissonetta 
collaris (Donovan). 
Aithyia GLOGER. 
Aythya BOIEK, Isis (von Oken), 1822, Heft V, col. 564 (type by subse- 
quent designation [Degland. Ornith. Europ., II, 1849, p. 455.], Anas ferina 
Linnaeus) (nec Aethya Dumont, quae Acthia Merrem { Alcidae]). 
Aithyia GLOGER, (Froriep’s) Notizen Gebiete Natur u. Heilk., XVI, No. 
18, March, 1827. col. 279 (nom. emend. pro tythya Boie: type, therefore, 
Anas ferina Linnaeus). 
Iperissds, mirabilis ; nétta, anas. 
“The Auk, XXXVI, No. 4, October, 1919, pp. 460-463. 
