15 
ture, save some remarks by Bélon, from 1555, which might be 
interpreted in that direction. In the same year a second note was 
published (1. c. p. 376), and some other birds were added: (Seriniis 
hartlanbi, S. leucopijgiiis); weavers (Lagonosticta inlnima, Aide- 
iiiosgne cantans, Estrilda cinerea; Miiniti orgzioora), parrots (Aga- 
pornis caiKt, Melopsittacus iindiilatiis), fowls (“jeune poulette de 
Houdan”), birds of prey (Tinniinciiliis alaudariiis). And in 1911 
a further communication was made, but only the same species are 
mentioned. Thus, from the observations now to hånd, I think we 
are justified in stating that in the class Aves generally the Wolffian 
duets are preserved for a long time in the females; they may be 
found in full-grown individuals (in some ducks in specimens at 
least 2 years old); but with inereasing age they probably atrophy 
and finally disappear completely. 
While the presence of Wolffian duets in normal female birds 
has been overlooked until quite recent times, the existence of these 
structures in females of abnormal condition was observed several 
years ago. The abnormal conditions now commonly comprised 
as “arrhenoidia“ — a term introduced in 1889 by Brandt — 
apparently are of rather frequent occurrence among birds. Cases 
have been mentioned from ancient — in faet the most remote — 
times, and a good many arrhenoid specimens have been anatomi- 
cally examined, often superficially, sometimes more carefully. Rather 
late, however, — from the eighties of the past century — has 
any attention been directed towards the Wolffian body and its 
duet. Such arrhenoid individuals in which the latter structures 
have been found of unusual development must, I think, be admit- 
ted as pseudohermaphroditic. 
In 1887 Tichomirow mentioned four hens, which did not show 
any male piumage, but crowed, possessed spurs and enlarged combs; 
in the cloaca were found the characteristic male papillæ, and se- 
minal (Wolffian) duets were present, but not twisted as in the cock; 
and their front part was not visible (?). The oviduct was in the 
main normal; the ovary (the left, no trace was found of the right) 
was present, but sterile; serial sections failed to show any egg- 
cells. Besides, T. describes a domestic duck, the piumage of which 
almost completely was that of a drake; the ovary was found rudi- 
mentary and sterile, the oviduct somewhat reduced, the cloaca 
without clitoris, but (slightly) asymmetrical as in the drake. Se- 
