13] 
entire femora, tibie and tarso-metatarsal bones, evidently belonging, by their proportional 
size and exact co-adaptation of articular surfaces, to the same species of bird, has enabled 
me to detect specific characters in the femur and tibia, by which this species, for which 
I propose the name of Dinornis casuarinus, clearly differs from both Dinornis struthoides 
and Dinornis didiformis, But I may be permitted to observe, that the reference of the 
solitary mutilated femur to the young of the Din. struthoides, which I am now enabled 
to correct, was a mistake on the safe side: the caution which refrains from multiplying 
specific names on incomplete evidence being less likely to impede the true progress of 
zoological science than the opposite extreme. 
The specific characters of Din. caswarinus (Pl. XXXVIIL.) and its distinction from 
Din. dromioides, with which it most nearly agrees in size, and especially in length, will 
be most prominently brought out by combining the descriptions of the bones of both 
species. 
The femur of the Din. casuarinus very little exceeds that of the Din. dromioides in 
length, but rather more in the circumference of the shaft, and very considerably in the 
development of the two extremities. The head is relatively larger, as Pl. XXIII. of the 
foregoing Memoir shows; the tuberosities below the middle of the back-part of the shaft 
are more developed: the rotular interspace between the condyles is both wider and 
deeper: the posterior half of the internal condyle is relatively much larger. But both 
the internal and the external longitudinal narrow ridges are more marked in Din. dro- 
mioides than in Din. casuarinus. 
The well-marked differences between the femora of these nearly similarly-sized species 
will be readily appreciated by comparing Pl. XXX VIII. with Pl. XXII. The specimen 
figured in Pl. XXXVIII, is rather less than other femora of the same species from the 
same locality. 
The most obvious distinction between the tibize of the Din. dromioides and Din. casua- 
rinus, in the relation of their thickness to their length, is shown in the ‘ Table of Ad- 
measurements’ and in Plate XX XIX. figg.1 & 2. The tibia of the Din. dromioides (fig. 1) 
is longer and more slender, corresponding with the character of the femur: the inter- 
space between the ectocnemial tuberosity (k) and the procnemial crista (p) at the proximal 
end is less than in Din. caswarinus, and the procnemial ridge continued down from the 
crista does not so soon gain the middle of the anterior surface of the shaft, and is con- 
tinued down the middle to the lower third before it inclines to the inner side: the ten- 
dinous groove leading to the osseous bridge (f) in front of the distal end is shorter and 
deeper. The orifice of the canal for the medullary artery is at the same distance from 
the top in the tibiz of both species. The antero-posterior thickness of the shaft of the 
tibia at its proximal third is markedly less in Din. dromioides than in Din. casuarinus. 
The difference in the plane and aspect of the surface between the anterior and fibular 
ridge in the Din. dromioides and Din. casuarinus is well-marked. 
The proportions of the tarso-metatarsus of Din. dromioides (Pl. XL, fig. 2) are, as 
s 
