EASTMAN: REMAINS OF STRUTHIOLITHUS CHERSONENSIS. 137 
would have been far less structural similarity to one another among the 
various groups than we find to prevail.” 
Dr. Ameghino's final conclusion is that the Stereornithes appear to 
show that the division of the class of birds into Ratite and Carinate is 
not fundamental, — a view which has been especially advocated by Mr. 
Lucas among American ornithologists. The latter,’ in a critical review 
of Ameghino’s work, speaks as follows : “ Apparently the main reasons 
for comparing such forms as Phororhachos and Brontornis with the 
Struthiones is because they are large and extinct, when, as a matter of 
fact, mere size is no reason for supposing a bird related to an ostrich ; 
while the pelvis of Phororhachos, with its aborted pubis, shows that this 
genus at least is very many removes from any Struthious bird. Nei- 
ther is Gastornis, with its primitive type of skull, any relation of the 
Stereornithes.” 
Precisely the same attitude is displayed by Mr. Andrews,? who denies 
that the Stereornithes have anything in common with Struthious birds 
or with the Gastornithide, neither are they by any possibility descended 
from Hesperornis. Says he: “The Stereornithes seem to be a hetero- 
geneous group of birds in all of which the wings were reduced and the 
bulk increased through the operation of some peculiar local conditions ; 
for instance, the land which they inhabited may have been an island on 
which no large carnivorous animals occurred. A similar example is 
offered by New Zealand, where the Dinornithide, Apteryx, Aptornis, and 
Onemiornis (all flightless birds of large size, and belonging to distinct 
orders) were formerly found. Indeed, there seems'to be no reason why 
at any time, from the late Secondary period onward, and in any region, 
similar groups of flightless birds might not have arisen under favorable 
circumstances. The Gastornithide may be another instance of such. 
In most cases such specialized races die out without leaving any descend- 
ants when the peculiar conditions to which they have become adapted 
pass away ; but the modern Ratitæ may be survivors of one or several 
ancient groups of such flightless birds.” 
Still more explicit are Mr. Lucas's views as to the nature and origin 
of the so-called Struthious birds, which he defines as “those generalized 
birds which through some special adaptation to their surroundings or 
freedom from enemies have been able to survive to the present day. 
Rhea and Struthio are typical examples of this. While it would be 
1 The Auk, New Series, Vol. XIII. (1896), pp. 62, 63. 
2 Remarks on the Stereornithes, a Group of Extinct Birds from Patagonia 
(Ibis, [7], Vol. IL p. 12). 1896. 
