Which flightless birds are of the genus 'Apteryx'?

Kiwis are flightless birds native to New Zealand, in the genus 'Apteryx' and family 'Apterygidae'. Approximately the size of a domestic chicken, kiwi are by far the smallest living ratites (which also consist of ostriches, emus, rheas, and cassowaries).

DNA sequence comparisons have yielded the surprising conclusion that kiwi are much more closely related to the extinct Malagasy elephant birds than to the moa with which they shared New Zealand.

Kiwi lay the largest egg in relation to their body size (up to 20% of the female's weight) of any species of bird in the world. Other unique adaptations of kiwi, such as their hairlike feathers, short and stout legs, and using their nostrils at the end of their long beak to detect prey before they ever see it, have helped the bird to become internationally well-known.

The kiwi is recognised as an icon of New Zealand, and the association is so strong that the term Kiwi is used internationally as the colloquial demonym for New Zealanders.