250 PROFESSOE OWEN ON THE GENUS DINORNIS. 



but is of very small size ; it leads, however, to a more expanded cavity, and may pro- 

 bably have given passage to one air-cell, penetrating for a little way into the neck of 

 the femur. At the distal end of the bone (fig. G) the articular production separating the 

 tibial from the fibular articular surface on the outer condyle is more ridge-like, and is 

 less produced backward, than in Binornis didiformis ^ 



§9. Tibia. 



The tibia of Binornis jiarmis (front view in figure of skeleton, PI. LI., oblique back 

 view, ib. PI. LVIII.) shows the chief generic characters of the bone in the great relative 

 breadth and height of the rotular or epicnemial plate, in the wide concavity between 

 this plate and the proximal articular surfaces, in having the same direction and 

 relative extent of the ridge for the attachment of the fibula, and in the completion by an 

 oblique bridge of bone of the canal transmitting the tendon of the ' extensor tibialis 

 anticus ' ". 



The large, slightly concave, articular surface for the inner condyle of the femur is 

 divided from the small convex surface for the inner side of the intercondyle by a well- 

 marked smooth wide groove. The prominence closing the outer end of that groove is 

 less developed than in Dinornis gravis'^ and most of the larger species. The procnemial 

 ridge subsides within 3 inches of its summit, and is not continued, as in I>. gravis', to 

 the groove for the extensor tendon. The ectocnemial process has a similar extent. The 

 fibular ridge subsides, as usual, at the entry of the meduUarterial canal, beyond which 

 a rough narrow tract, not rising above the surface of the bone, indicates the continua- 

 tion of the ligamentous attachment of the slender distal half of the fibula to the tibia. 

 On the opposite side of this bone commences, at .3 inches from the distal end, a well- 

 marked, rough, slightly depressed surface, gradually widening to 7 lines across, where 

 it terminates | inch above the distal border of the inner (' tibial ') condyle. 



The anterior part of the distal articular surface of the tibia has not the mid 

 rising interrupting the transverse concavity as in Binornis gravis^. For the rest, the 

 distal articular and other characters of the leg-bone closely conform to the dinornithic 



type. 



I may remark that in comparison with the Bustard {Otis tarda), to which Binornis 

 parens is little superior in size, the tibia is thicker relatively to its length, and, with 

 other osseous characters of the legs, is indicative of the more powerful actions and 

 varied uses to which the Moas of New Zealand applied their feet. 



Both proximal and distal epiphyses are as thoroughly confluent with the diaphysis 

 in the present small species as in the tibia of the largest Moas. 



' Compare fig. 6, PI. LVI. of the present Memoir with fig. 3, pL xxxv. Trans. Zool. Soc. vol. iii. 

 ' See these and other characters defined and figured, of the natural size, in Trans. Zool. Soc. vol. iii. 1843, 

 pis. xxT., xxvi. ' Trans. Zool. Soo. vol. viii. pi. lix. fig. 3,d, 



* Ihid. vol. viii. pi. lix. fig. 1, </. ' Tom. cit. pi. lix. fig. 2, u. 



