364 PROFESSOR OWEN ON THE GENUS DINORNIS. 
oval form, 1 inch 9 lines in length, 7 lines in extreme breadth, and is divided from the 
back part of the articular surface of the outer trochlea (1v) by a smooth tract about 
4 lines in breadth. A narrow, oblong, rough tract at the proximal part of the shaft 
behind the ectometatarsal ridge (ib. fig. 2, 4) may serve also for gastrocnemial insertion ; 
but it is divided from the lower ectogastrocnemial tract by a smooth surface of the mid 
part of the metatarsal, about an inch and a half in extent in one instance, and two 
inches in the specimen figured in Pl. LVIII. The narrow tract from the entogastro- 
cnemial tuberosity (y) is more feebly marked, if it be discernible, in Dinornis crassus. 
The ectogastrocnemial surface is also less defined, and is continued upwards as a more 
or less conspicuous ridge to within a few lines of the ectometatarsal rough surface in 
Dinornis crassus. 
The fore part of the entotrochlea (fig. 1, 11) is broader relatively to the hind part in 
Dinornis gravis than it is in Dinornis crassus. The outer side of the fore part of the 
ectotrochlea (1v) is more conyex or tuberous, and is less defined from the ectotrochlear 
fossa than in Dinornis crassus. 
The interspaces of the trochlee are narrower in Dinornis gravis; and this character 
is the more easily seized, inasmuch as the breadth of the three trochlez is almost 
the same in the two species, notwithstanding the difference in the length of the 
metatarsi. 
Dinornis gravis had a stronger and stouter foot, relatively, than Dinornis crassus ; 
and the muscular force working it was more powerful, as is indicated by the insertional 
ridges and tracts (9, 7, 2). 
In a metatarsus of Dinornis crassus, 8 inches 6 lines in length, the greatest breadth of 
the mid trochlea is 1 inch 8 lines; in a metatarsus of Dinornis gravis 7 inches 9 lines 
in length the greatest breadth of the mid trochlea is 1 inch 10 lines. 
The general characters of the bone, with the disposition and aspects of the distal 
trochlea, are much alike in the two species; but the differences above defined impress 
me with the conviction that ornithologists would find the birds to which the metatarsi 
of Din. crassus and Din. gravis belonged, if they had them entire to compare, to be 
distinct species. 
The number of the living species of Casuarius which have of late years been dis- 
covered in detached remnants of the great Australasian continent, show much more 
striking differences in plumage and dermal appendages than could have been suspected 
from any differences which are discernible in the bones of the legs; and these differences, 
when most distinct, are less marked than those above demonstrated in the metatarsals 
of the species of Dinornis which least differ in general size. 
The tibia of Dinornis gravis (Pl. LYX.), in comparison with that of Dinornis crassus, 
which it most resembles, has a stronger or thicker shaft in proportion to its length’. 
The character of the metatarsal bone of Dinornis gravis is here repeated, but in a minor 
' See Table of Admeasurements, p. 371. 
