The frontals are broad and convex, rising abruptly (as in _Didunculus_) above the coalesced cranial ends of the nasals and premaxillary (Pl. III.); in _Didus_ the breadth greatly exceeds the length of the interorbital frontal convexity, as compared with _Didunculus_, and the convexity reigns in the transverse as well as the antero-posterior direction; in _Didunculus_, however, it is less concave transversely than in _Goura_. In the breadth or thickness of the interorbital septum _Didus_ resembles _Apteryx_ and _Palapteryx_ and shows the same pneumatic cancellous structure. The posterior olfactory chambers are partially divided, as in _Dinornis_, by an upper median septum; each compartment, which is 7 lines across and an inch in length, is perforated posteriorly by an olfactory foramen more than a line in diameter, from which grooved impressions of ramifications of the nerve diverge upon the hind and upper wall of the chamber: external to the olfactory foramen is a longer one for the passage of a vein into the fore and inner part of the orbit. The cranial ends of the nasals and nasal process of the premaxillary (Pl. XI. fig. 1, 22) are flat, depressed, thin plates; the latter at its junction with the frontal is 6 lines broad, partially divided by a median groove above and a ridge below, and by short linear fissures from the nasals: the forward extension of these bones is feebly indicated by linear grooves terminating at the outer margins of the nasal branch of the premaxillary, about 4 inches from its vertical end. The proportion of the base of the upper mandible attached to the frontal contributed by the nasals is the same as that indicated in the ‘Proc. Zool. Soc.’ _l. c._ The nasal branch of the premaxillary presents a full elliptical transverse section where it quits the maxillary processes, losing both depth and breadth as it recedes to join the nasals; here it retains its breadth, viz. 6 lines, but continues to be thinned off vertically to the plate above named joining the frontal. The under surface of the narrower part of the stem is angular, the upper one being gently convex.