_Oyseaux bleus_ Le Sieur D.B., Les Voyages aux Isles Dauphine and Bourbon, pp. 170, 171 (1674). _Apterornis coerulescens_ Selys-Longchamps, Rev. Zool. 1848, p. 294. The original description of the Sieur D.B. (Dubois) is as follows (translated):--"_Oyseaux bleus_: As big as the Solitaires; they have the plumage entirely blue, the beak and the feet red and made like those of fowls; they do not fly at all, but run extremely quickly, so that a dog can hardly catch them; they are very good." Habitat: Bourbon or Réunion. Dubois gives the size of these birds as the same as that of a big goose and the feet as being like those of a fowl: I have, therefore, in reconstructing the plate of this bird, had it made intermediate in structure between the New Zealand _Notornis_ and _Aptornis_, which were evidently its nearest allies. {147} APTORNIS OWEN. Differs from _Dinornis_, _Palapteryx_ and _Notornis_ in having an articular surface for a very strong hind toe, and the tarso-metatarsus of a conformation more nearly resembling that found in the _Dodo_, but shorter and thicker than in the latter. In addition, the strong calcaneal process, perforated by a complete bony canal for the tendon at the back part of the proximal end of the tarso-metatarsus; the perforation above the interspace between the condyles for the middle and outer toes; and the more posterior position for the condyle for the inner toe all prove the distinctness of this genus. Type: _Aptornis otidiformis_. APTORNIS OTIDIFORMIS (OWEN). _Dinornis otidiformis_ Owen, Trans. Zool. Soc. III, p. 247, pls. XXV and XXVI, fig. 5 (1844). _Aptornis otidiformis_ Owen, ibidem p. 347 (1848). This is the North Island form, and I must refer my readers to Owen's description, only remarking that Mr. Hamilton, Trans. N.Z. Inst. XXIV, p. 179, says the vertebrae assigned by Owen to _Cnemiornis_ all belong to _Aptornis_. Locality of type tibia: Poverty Bay, North Island, New Zealand; collected by Rev. Wm. Williams in 1842. {148} APTORNIS DEFOSSOR OWEN. _Aptornis defossor_ Owen, Trans. Zool. Soc. VII, pp. 353 to 366, pls. 40-44 (1871). The skull differs from that of _A. otidiformis_ by the vertical surface of the descending part of the occiput being less deeply concave, the occipital foramen relatively smaller. The hind part of the base of the alisphenoid is more produced and tuberous outside the end of the hyoid process of the paroccipital in _A. defossor_. The chief other differences in size, according to Owen, are as follows:--