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shaft: they are separated by a tract of half an inch in the Dinornis 
struthioides, and terminate below in two tuberosities. The corre- 
sponding ridge formed by the meeting of the vasti-muscles along the 
fore part of the shaft is shorter in Din. gracilis than in Din. stru- 
thioides. 
The most marked distinction, however, is presented by the distal 
extremity of the bone, which is not only relatively less expanded in 
the Din. gracilis, but the rotular groove is narrower, and is bounded 
laterally by condyloid eminences of more nearly equal length; the 
external one not rising so high up, nor describing the sigmoid curve 
in descending, as in the Din. struthioides. The rotular groove in the 
Din. gracilis is impressed by a transversely oval rough depression, 
at its upper part, with sharp lateral borders ; which depression does 
not appear in any of the femora of the Din. struthioides. The 
popliteal space is triangular and better defined in the Din. gracilis ; 
the fibular groove is shorter and less angular, and the rough deep pit 
above it is smaller. The tibial surface on the inher condyle is rela- 
tively smaller. 
Tibia. 
The same character is repeated on the proximal end of this bone, 
where the surface applied to the inner condyle is absolutely smaller 
than in the Din. struthioides, although the entire bone, as shown in 
the subjomed admeasurements, is longer in the Din. gracilis: it is 
also, as the name of the species implies, more slender in proportion 
to its length. 
D. gracilis. 
in. lin. 
The entire length of the bone is ........ se a ce AO 
The transverse breadth of its proximalend.... 5 2 
The transverse breadth of its distal end ...... yee a, 
The circumference of the middle of the shaft . . 4 6 
The fibular ridge extends down the shaft .... 9 6 
But this ridge commences nearly 3 inches below the back part of 
the proximal end of the bone, nearer the outer side than in the 
D. struthioides: it is interrupted by an oblique smooth tract at the 
point indicated in the admeasurement, where the medullary artery 
penetrates the bone ; it then reappears about one inch and a half be- 
low the interruption, and soon gradually subsides. This second lower 
part of a fibular ridge is better marked than in the Din. struthioides. 
The relative size and position of the procnemial and ectocnemial 
ridges are much the same as in the tibia of the Din. struthioides and 
Din. dromioides. 
Metatarsus. 
The difference between the Din. struthioides and the Din. gracilis 
is more obvious at first glance in a comparison of their metatarsi than 
in that of the above described bones ; especially to an eye accustomed 
to the comparison of the metatarsi of the different species. The 
superior length and slenderness of that bone in the Din. gracilis 
