54 Evolution and Adaptation 
Fleischmann again fails to point out that the geological 
period in which the remains of archzopteryx were found, 
is the one just before that in which the modern group of 
birds appeared, and, therefore, exactly the one in which the 
theory demands the presence of intermediate forms. This 
fact adds important evidence to the view that looks upon 
archzopteryx as a form belonging to a group from which 
living birds have arisen. That a number of recent paleon- 
tologists believe archzopteryx to belong to the group of 
birds, rather than to the reptiles, or to an intermediate group, 
does not in the least lessen its importance, as Fleischmann 
pretends it does, as a form possessing a number of reptilian 
characters, such as the transmutation theory postulates for 
the early ancestors of the birds. 
The origin of the mammalian phylum serves as the text 
for another attack on the transmutation theory. Fleischmann 
points out that the discovery of the monotremes, including 
the forms ornithorhynchus and echidna, was hailed at first as 
a demonstration of the supposed descent of the mammals from 
a reptilian ancestor. The special points of resemblance be- 
tween ornithorhynchus and reptiles and birds are the com- 
plete fusion of the skull bones, the great development of 
the vertebrz of the neck region, certain similarities in the 
shoulder girdle, the paired oviducts opening independently 
into the last part of the digestive tract (cloaca), and the 
presence of a parchment-like shell around the large, yolk- 
bearing egg. These are all points of resemblance to reptiles 
and birds, and were interpreted as intermediate stages be- 
tween the latter groups and the group of mammals. In 
addition to these intermediate characters, ornithorhynchus 
possesses some distinctive, mammalian features — mammary 
glands and hair, for instance. Fleischmann takes the ground, 
in this case, that there are so many points of difference be- 
tween the monotremes and the higher mammals, that it is 
impossible to see how from forms like these the higher 
