EASTMAN: REMAINS OF STRUTHIOLITHUS CHERSONENSIS. 143 
lemurs, insectivora, rodents, and reptiles now inhabiting the island bear 
the stamp of great antiquity. It is true that Zpyornis remains, so far 
as known, are confined to deposits of supposed Pleistocene age, and the 
material itself is inconsiderable.'| The deficiency may be partially ac- 
counted for owing to lack of exploration, and imperfection of the pale- 
ontological record, especially as concerns land birds. But if it be 
objected that a continuous Tertiary history implies a higher degree of 
specialization and greater specific variation than we have any evidence 
of, we must not forget that here the action of natural selection was 
more or less suspended, owing to the abundance of food, absence of 
carnivorous or other powerful enemies, and generally mild conditions. 
The same causes produced the same effects upon the ancestors of py- 
ornis as upon the moas, of which Captain Hutton affirms, ‘“ Under such 
favorable circumstances the conditions of life were very easy, and the 
birds grew larger and fatter, more sluggish and more stupid,” — until, 
in fact, they became effete and were finally extirpated. 
On the assumption that the forerunners of Zpyornis have inhabited 
Madagascar ever since its separation from the mainland, it is not surpris- 
ing that this genus should have to stand by itself as the representative 
of a distinct suborder. Some resemblances to the Struthio-Rhea branch 
of the Ratite are observable, to be sure, — even the egg shells having a 
remarkably similar structure, as shown by Nathusius, — and anatomists 
like Firbringer, Milne-Edwards, and Grandidier have endeavored to 
show even greater similarity to Dromeus and Casuarius, which are 
regarded as the most primitive of existing Ratite. But all are agreed 
that the differences far exceed the resemblances, being in fact funda- 
mental. To us it seems that the amount of divergence from other 
known types, living and fossil, coupled with the slower rate of variation 
affectiug insular forms, and, above all, the generalized characters ob- 
served in Apyornts, go to show that this bird is far from being a modern 
derivative, but is the last of a very ancient race. We see no impropri- 
ety in supposing that its flightless ancestors inhabited the Madagascar 
region when it was still a part of Africa, and that other descendants 
may have migrated northward into Europe during the early Tertiary. 
1 Andrews, C. W., Note on a nearly complete Skeleton of Zpyornis from Mad- 
agascar (Geol. Mag., Dec. 4, Vol. IV. pp. 241-250), 1897. Burckhardt, R., Ueber 
pyornis (Palaeont. Abhandl. Dames und Kayser, Vol. II. Heft 2), 1893. 
