PROFESSOR OWEN ON THE GENUS DINORNIS. 119 
New Zealand I found two generic types of skull, and referred in 1848 one of these 
(Vol. III. pl. 52. figs. 1-6) to Dénornis, the other (ib. pl. 54) to Palapterya. I subse- 
quently discovered a type of leg and foot generically distinct from those which had been 
referred respectively to Dinornis and Palapteryx; and for that type I proposed the 
genus Aptornis, to which genus I was then led to refer the very remarkable skull 
figured in pl. 52, tom. cit.’ 
Successive evidences of cranial characters of different species of Dinornis, from the 
largest downwards, were far from showing the distinctions which, in the skull of 
Aptornis, had originally led to a generic division of the larger extinct wingless birds of 
New Zealand; and accordingly, retaining the name Dinornis for the D. giganteus and 
allied species to which, as originally known by vertebree, pelvis, and limb-bones, that 
generic name had been applied, I was driven, after ascertaining their true cranial 
characters, to rest the distinction of Palapteryx on the presence of the small back toe, 
determined in the large robust species of the Middle Island (Palapteryax robustus*), and 
its seeming absence in the more slender Dinornis giganteus of the North Island. Sub- 
sequently I was led to doubt the generic value which had been assigned to that 
reduced, not to say abortive, digit, probably variable as to its existence; and I gave 
up the application of the character, from the consideration that the ligamentous attach- 
ment might fail to leave sufficient indication on the metatarsal bone in some cases. The 
range of variation in the cranial characters of species unequivocally of either Dinornis 
or Palapteryx did not appear to me to support a continuance of those generic sections ; 
and of late years I have, therefore, practically dropped ‘‘ Palapteryx,” and described 
additional facts and evidences of these extinct birds under the old generic term Dinornis. 
No doubt, apart from the Apterygian character of the back toe (7, fig. 1, pl. 1, Vol. IV.), 
if even it had been determined without question to be constantly present in certain 
species and absent in others, the singularly massive proportions of the limb-bones in 
such species as D. elephantopus and D. crassus might lead one, prone to generic sections, 
to found a genus for such strong-limbed birds. But D. robustus and D. maximus, with 
the series of Moas dwindling to a form smaller than any which I have yet described, but 
equally worthy of being named, illustrate the transitional steps in the derivation of such 
species, due to inherent tendencies operating independently of individual volitions, and 
under circumstances affording no obvious or intelligible selective influences. Guided, 
however, by the Linnean methods of making known these animated forms, and accepting 
genera as they stand in natural families of modern ornithological systems, the two well- 
marked modifications of sternum which I have now been enabled to describe might 
justify the restitution of the term Palapteryx to such thick-limbed kinds as Pal. ele- 
phantopus, Pal. crassus, and Pal. robustus. 
1 «On Dryornis (part v.): containing a description of the Skull of D. giganteus &c.,” read Noy. 1850, 
Trans. Zool. Soc. vol. iv. pp. 59, 62. 
* Trans. Zool. Soc. vol. iv. p. 2, pl. 1 (Memoir, part iv. read Feb. 1850). 
