574 TOOTHED AND LIZARD-TAILED BIRDS. 
For a long period the marshes of Madagascar have yielded 
the eggshells of enormous extinct birds, in search of which the 
natives are accustomed to probe with iron rods; the largest of these eggs having 
a longer circumference of upwards of thirty-six inches, and a girth of thirty 
inches. For the monster birds that laid these eggs (which, by the way, may well 
have given origin to the far-famed roc of Arabian romance) the name of A/pyornis 
was proposed; and in the course of time naturalists were rewarded by the dis- 
covery of its bones. Some of these recently disinterred indicate a bird of larger 
build than the most gigantic moa; the metatarsus being especially remarkable 
for its massiveness. Certain of these birds appear to have had: four toes; and 
they all differ from the moas in the absence of a bony bridge at the lower end 
of the tibia. They form the family 4pyornithide. 
#pyornis. 
TooTHED AND LizARpD-TAILED Brrps. 
There remain for brief consideration certain extinct birds, from 
formations of earlier age than the Tertiary, which differ from 
the whole of those of the present day either in the possession of teeth in the jaws, 
or of these, coupled with the retention of a long lzard-lke tail, and certain other 
features in the skeleton indicative of affinity with reptiles. 
Of the toothed birds (Odontornithes), as distinct from the lizard-tailed birds 
which are likewise provided with teeth, there are two very well - marked 
modifications, both of which have been obtained from strata in the United States, 
corresponding approximately in age with the Chalk and associated formations of 
Europe, and hence frequently spoken of as Cretaceous birds. In their general 
organisation these birds approximate so closely to the ordinary Carinate birds of 
the present day, that they may well be included in the same subclass, of which 
they will constitute a separate series characterised by the possession of teeth, 
and likewise by the circumstance that the two halves of the lower jaw remain 
completely separate in front, instead of having a solid bony union. Of these 
toothed birds the one type is known as Jchthyornis, and comprises somewhat 
gull-like birds characterised by having a numerous series of teeth implanted 
in distinct sockets, and also by the vertebre or joints of the back-bone articu- 
lating with one another by means of cup-like surfaces, whereas in the neck 
(and generally also in the back) of all existing birds, such surfaces are saddle- 
shaped. Although the osteology of Ichthyornis has many resemblances to that of 
the gulls, this being especially shown in the skull, which is regarded by Dr. 
Schufelt as coming very close to that of the skimmer, the skeleton differs, among 
other points, by the circumstance that there is no projecting process on the outer 
side of the lower end of the humerus. Hence, although it is quite within the 
bounds of probability that these birds may be ancestral types of the modern gulls, 
it is by no means certain that they should be included in the same group. 
With Hesperornis we are confronted with a totally different type, in which 
the teeth were implanted in an open groove, while the wings were rudimentary, 
and the keel of the breast-bone was wanting, although the vertebra resembled 
those of existing birds in articulating together by saddle-shaped surfaces. In 
Toothed Birds. 
