364 PROFESSOR OWEN ON THE GENUS DINORNIS. 
affinity of Aptornis to Notornis than to Dinornis. The basilar (basioccipito-sphenoidal) 
platform is pentagonal, the anterior angle projecting below the base of the rostral pro- 
duction’; the Eustachian canals have a corresponding adjustment. The pterapophyses 
are obsolete in both Aptornis and Notornis. The articular cavities for the tympanic are 
two in each mastoid, similarly divided by a pneumatic slit. Notornis has muscular 
productions from the outside of the mastoid, answering to the mastoid process—the 
midmastoid and premastoid ones; but the two latter are mere ridges, or, if the pre- 
mastoid be produced, it ends freely in a point, as in smaller Coots*. The nasal branch 
of the premaxillary coalesces with the nasals and frontals in Aptornis and Notornis. 
The maxillary branch of the nasal is similarly directed, leaving an antorbital vacuity, 
with a long oval nostril, almost pointed at the upper, smaller end. ‘The ossification of 
the fore part of the premaxillary hides from view the prenasal septum. In the 
mandible the angle is deflected in Ocydromus, Porphyrio, and Notornis as in Aptornis. 
The variation of palatal structure might be a bar to an approximation of Aptornis to 
Notornis and smaller Coots, were it not such in other families, united by sounder ties of 
organic character, as to show its low taxonomic value. 
From another point of view the peculiarities of the skull in Aptornis may be con- 
sidered in relation to the food of the bird and the work to which its long adze-like beak 
was put. 
I infer this work to have involved frequent strong and deep thrusts into the ground, 
and that the quest was for animal, not vegetable matters. I have heard casually and 
vaguely of the great number, size, and unusual colour of the earthworms of New 
Zealand; and it is probable that a rich field here remains to be explored by the 
helminthologist. 
The strange appearance of the parasitic cryptogam, Sphwria, sp., when it has 
achieved its growth at the cost of the caterpillar infested, has made us familiar with 
the burrowing habits of at least two species of New-Zealand Nocturnal Lepidoptera 
(Cheiragria virescens and Cheir. rubroviridens) at the larval stage of their existence. 
Such larvee and earthworms were probably the food of Aptornis. 
The cranial part of the skull may be regarded as the base or handle in which the 
digging adze was set; its expansion, radiating from the occipital condyle as a centre 
(Pl. XLL fig. 1, 1), speaks decisively, by its superficial accentuation, to the size and 
power of the muscles therein implanted: the special development of the leverage-tract 
below the centre of motion relates to adequate fixation of the muscular powers that 
were to strike down the adze into the soil. 
The muscles working the beak as part of the head are better developed in the ground- 
piercing Apteryx than in most birds, as will be estimated by the myotomist who may 
1 Trans. Zool. Soe. vol. iii. pl. 56. fig. 11. 
2 In a Porphyrio smaragnotus I haye seen the tendon of each crotaphyte muscle ossified, and extending from 
a part of the temporal fossa answering to the ‘‘ midmastoid” as far as its insertion into the mandibular ramus. 
