I34 THE AMERICAN NATURALIST. [Vor. XXXV. 
. Finally, Hubrecht mentions the results of Klaatsch in con- 
nection with polyphyletic origin. He quotes from Klaatsch 
as follows: * Dadurch wird man zu der Annahme gedrängt, 
dass die Hufthiere sich ganz direkt an jene oben dargestellte 
Urform der Saugethiere anschliessen, deren hypothetische 
Vertreter man als Taschenthiere oder Bursalia von den Beu- 
telthieren oder Marsupialia unterscheiden kann. Es wird 
denkbar, dass die Hufthiere niemals ein Marsupial- 
stadium durchliefen."! 
If we follow Klaatsch throughout the course of his paper, 
we find that he recognizes a primary condition of the mammary 
apparatus consisting of paired mammary pouches lodging the 
mammary glands. Out of these are formed independently the 
incipient marsupium of monotremes and the perfect marsupium 
of marsupials. In the artiodactyl ungulates these pouches 
show no signs of marsupium formation ; they are converted 
into the tubular teat cavities. He accordingly concludes that 
the artiodactyl ungulates have not passed through a marsupial 
stage (Marsupialstadium). 
Although this is doubtless a true interpretation, it can- 
not be regarded, as Hubrecht suggests, as pointing to poly- 
phyletic origin; for it is not our object in contemplating 
polyphyletic origin to prove that, for example, the artiodactyl 
ungulates have not passed through a marsupial stage, but 
that they have not passed through a metatherian stage. The 
results of Klaatsch confirm that which Huxley, notwithstand- 
ing the meagerness of his evidence, perceived, namely that 
the marsupium is not a transitional character but a special 
character of marsupials.? 
We may again refer to the opinion of Wilson and Hill ('97, 
P. 579). Concerning the mammary pouches of Klaatsch they 
speak as follows: «Such a rudimentary or primitive condition 
must have been characteristic of the common stock of both 
Metatheria and Eutheria, and was only a marsupial one in the 
sense that Echidna is now marsupial.” From this it is clear 
that they do not regard Klaatsch's results as at all indicative 
of polyphyletic origin. 
! Klaatsch ('92 p. 369). 2 Huxley (’80, p. 656). 
