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MESSRS. E. M. BALEOTJR AHD W. N. PARKER OK THE 
The relationship of the genital ducts to the kidney ducts in Amici and Polypterus 
is somewhat different from that in the Chondrostei and Lepidosteus. In Amia the 
ureters are so small that they may be described rather as joining the coalesced genital 
ducts than vice versd, although the apparent coalesced portion of the genital ducts is 
shown to be really part of the kidney ducts by receiving the secretion of a number 
of mesonephric tubuli. In Polypterus the two ureters are stated to unite, and open 
by a common orifice into a sinus formed by the junction of the two genital ducts, 
which has not been described as receiving directly the secretion of any part of the 
mesonephros. 
It has been usual to assume that the genital ducts of Ganoids are true Mullerian 
ducts in the sense above defined, on the ground that they are provided with a 
peritoneal opening and that they are united behind with the kidney ducts. In the 
absence of ontological evidence this identification is necessarily provisional On the 
assumption that it is correct we should have to accept the second of the two alter¬ 
natives above suggested as to the development of the posterior parts of the oviduct 
in Lepidosteus. 
There appear to us, however, to be sufficiently serious objections to this view to 
render it necessary for us to suspend our judgment with reference to this point. In 
the first place, if the view that the genital ducts are Mullerian ducts is correct, the 
true genital ducts of Lepidosteus must necessarily be developed at a later period than 
the secondary attachment between their open mouths and the genital folds, which 
would, to say the least of it, be a remarkable inversion of the natural order of 
development. Secondly, the condition of our oldest larva shows that the Mullerian 
duct, if developed later, is only split off from quite the posterior part of the segmental 
duct; yet in all types in which the development of the Mullerian duct has been 
followed, its anterior extremity, with the abdominal opening, is split off from either 
the foremost or nearly the foremost part of the segmental duct. 
Judging from the structure of the adult genital duct of other Ganoids they must also 
be developed only from the posterior part of the segmental duct, and this peculiarity 
so struck one of us that in a previous paper* the suggestion was put forward that the 
true Ganoid genital ducts were perhaps not Mullerian ducts, but enlarged segmental 
tubes with persisting abdominal funnels belonging to the mesonephros. 
If the possibility of the oviduct of Lepidosteus not being a Mullerian duct is 
admitted, a similar doubt must also exist as to the genital ducts of other Ganoids, and 
we must be prepared to show that there is a reasonable ground for scepticism on this 
point. We would in this connexion point out that the second of the two arguments 
urged against the view that the genital duct of Lepidosteus is not a Mullerian duct 
applies with equal force to the case of all other Ganoids. 
The short funnel-shaped genital duct of the Chondrostei is also very unlike 
* F. M. Balfour, “On the Origin and History of the Urinogenital Organs of Vertebrates,” Journ. of 
Anat. and Phys., vol. x., 1876. 
