Head less flattened than in the _Dinornithidae_, much longer and narrower. Brain case much greater in volume. Occipital condyle strongly pedunculate. Temporal fossae deep and narrow. The basisphenoid has on each side a well marked pterygoidal apophysis. The lower mandible is straight and stout, recalling somewhat that of _Rhea_, but the maxillary branches are higher and stouter. The symphysis is long, contracted, and hollowed out in the shape of a ladle. The sternum presents many affinities to that of _Apteryx_. It is a thin plastron, flattened, and much widened. The coracoidal articular surfaces similar to those of _Apteryx_. The Coraco-scapulars are feeble, and have so faint an articular surface that the humerus must have been rudimentary. Hallux absent, outer digit has five, the middle digit four, and the inner digit three phalanges. There are three genera and twelve species. A striking character is that in the genus _Aepyornis_ the proximal extremity of the tarso-metatarsus is larger than the distal extremity, a feature not found in the majority of other birds. Monsieur Grandidier has expressly pointed out that _Aepyornis_ had only three toes, I cannot, therefore, understand why Messrs. Lydekker and Evans both state that the hallux is present. {222} In spite of the researches of Messrs. Grandidier, Last, and Forsyth Major and the large collections sent home by them, the number of _Aepyornis_ bones is infinitesimal compared with the vast masses of bones of the _Dinornithidae_ contained in the museums. This paucity of material quite prohibits us from making a critical study of the described species, so that we are at present unable to say if too many or too few species have been diagnosed. I am inclined, however, to think that if we ever get complete skeletons of the larger forms, _Ae. grandidieri_ and _Ae. cursor_ will prove to be sexes of one species, and also _Ae. titan_ and _Ae. maximus_. For the present, however, the measurements are too different to allow of their being united without further investigation. The three genera are as follows:-- AEPYORNIS T. GEOFF. _Aepyornis_ Geoffroy Saint Hilaire. _Epiornis_ Geoffroy Saint Hilaire. _Epyornis_ Auct. MULLERORNIS MILNE-EDWARDS & GRANDIDIER. _Mullerornis_ Milne-Edwards and Grandidier. FLACOURTIA ANDREWS. _Flacourtia_ Andrews. _Mullerornis_ Milne-Edwards and Grandidier (part). {223} AEPYORNIS GEOFF. Characters same as those of the family; but in opposition to _Mullerornis_ the species are very heavy, ponderous, and clumsy, the bones being both actually and comparatively much stouter. Differs from _Flacourtia_ in not having an ossified boney bridge over lower end of groove for adductor of outer digit. Type: _Aepyornis maximus_ Geoff. Number of species: 9. AEPYORNIS TITAN ANDR. _Aepyornis titan_ Andrews, Geol. Mag. 1895, p. 303.