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 ^Epyornis 

 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 JBpyornithidce. 



TOOTHED AND LIZARD-TAILED BIRDS. 



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 lizard-like 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 Ichthyornis, and comprises somewhat 

 gull-like birds characterised by having a numerous series of teeth implanted 

 in distinct sockets, and also by the vertebrae 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 vertebrae resembled 

 those of existing birds in articulating together by saddle-shaped surfaces. In 



