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the larger tarsometatarsal bones Nos. 1567 and 1574, it will be found 

 that whilst the circumference of the middle of the shaft in No. 1567 is 

 less than one-third of the entire length of the bone, and that of No. 

 1574 is rather more than one-third, that of the present small metatarsal is 

 a little more than one-half. Again, the breadth of the distal end of the 

 present metatarsal is nearly one-half the length of the bone ; in No. 1574 

 it is just one-third ; in No. 1567 it is two-sevenths. The difference is well- 

 marked in the proportions of the breadth or lateral diameter of the shaft 

 as compared with the thickness or antero-posterior diameter, but is less be- 

 tween No. 1567 and No. 1574 than between either of these and the pre- 

 sent bone. This small metatarsal also presents differences of configuration 

 when compared with the larger metatarsals, besides those indicated by 

 the admeasurements, which assist in establishing a distinction of species : 

 the distal end of the bone is more suddenly expanded than in the larger 

 specimens ; the proximal posterior prominence of the middle division of 

 the metatarsal more rapidly subsides as it descends ; there is no longi- 

 tudinal channel continued downwards from the hole on the inside of this 

 prominence, such channel being as well marked in the larger metatarsals 

 as the outer one : the shallow concavity on the outside of the prominence 

 is relatively broader in the smaller metatarsal. The inner concavity of 

 the proximal articular surface is relatively deeper in the present bone. 

 The median longitudinal concavity, below the rough depression at the 

 anterior part of the proximal end of the bone, is hardly discernible in 

 No. 1585, but is well marked in Nos. 1567 and 1574. Finally, the small 

 metatarsal, which is but half the length of No. 1574, and but one-third 

 the length of No. 1567, has all the characters of the compound tarso- 

 metatarsal in a fully mature bird. There is no trace of the original sepa- 

 ration of the proximal epiphysis ; and, with respect to that of the three 

 primitive constituents of the shaft of the bone, it is as obscurely indicated 

 as in other old tridactyle birds, by the two small holes at the back and 

 upper part of the bone. I have inferred, therefore, from the present small 

 metatarsal, the former existence of a distinct species of three-toed Stru- 

 thious bird, differing from the larger species of Dinornis in its relatively 

 shorter and broader metatarsus. In this character the present species of 



