11 
It is a well known fact that in Vertebrates generally — leaving 
aside the Teleosts and some other fishes — rudiments of two sets of 
tubes, the Wolffian (mesonephric) ducts and the Miillerian ducts 
are formed in every embryonic specimen, without regard to its 
future sex as a male or a female. In the Vertebrata amniota, during 
development and sex-differentiation, the Wolffian ducts undergo 
abortion in the females, and the Miillerian ducts develop into ovi- 
ducts, while in the males the Miillerian ducts are obliterated, and 
the Wolffian ducts persist as seminal ducts. In many cases the 
Wolffian ducts seem to disappear completely in the females, and 
the Millerian ducts to do the same in the males; but in some 
Cases traces of the ducts, developing in the opposite sex, are known 
normally to be preserved, viz. among reptiles and mammals (f. 
ex. in 2 of many mammals "Gartnerian (or Malpighian) ducts,” 
in g "uterus masculinus”, ,,sessile hydatide”); and abnormally 
the ducts characteristic of the opposite sex may in some specimens 
develop to such an extent, that we are entitled to speak of these spe- 
cimens as pseudohermaphroditic. This being the case among reptiles 
and mammals there seems to be no obvious reason why birds should 
form an exception. Nevertheless I have not found recorded any 
case of Millerian ducts preserved in undoubtedly male birds, 
neither normally as rudimentary remnants, nor abnormally as testi- 
fying pseudohermaphroditismus. In the literature I have only been 
able to detect the following two cases which to a certain degree 
may be said to point in the one or other direction. 
The first case concerns the African ostrich. In Carus and 
Otto: Érlåuterungstafeln zur vergleichenden Anatomie, Heft V, 
1840, Taf. VII, Fig. 3, is represented the cloaca with appertinent 
Structures of Struthio camelus $. The explication of the figure 
Tuns: "In der gedffneten Kloake zeigen sich zu beiden Seiten, be- 
Sonders deutlich aber auf der linken (a und a') spiral-trichterfår- 
mige Vertiefungen, in welchen sich die blinden Analoga mit den 
hier beim Weibchen beginnenden Ovidukten nicht verkennen las- 
Sen,” The said structures — two pits of unequal size — are seen 
laterally to the large seminal papillæ. Possibly these structures 
May be found normally in male ostriches; but any rudimentary 
real oviducts, connected with the pits, are neither mentioned nor 
Ågured. The second case is a domestic fowl described by Brandt 
