PROFESSOR OWEN ON THE GENUS DINORNIS. 11 



ing the head stands inwards at right angles. The head is impressed by a large pit for 

 the " ligamentuin teres." The great trochanter rises above the level of the smooth upper 

 surface continued to it from the head : there is a well-marked ridge which extends from 

 the inner and back part of the shaft of the bone to the upper and back part of the inner 

 condyle ; in this character it resembles the femur of the Apteryx, as well as in its rela- 

 tive length to the tibia. The inner condyle reaches downwards nearly as far as the 

 outer condyle. The fibular fossa, outside the outer condyle, is well-marked : above it 

 is a deep and rough depression. The fore part of both condyles is more prominent than 

 in the femora of Dinornis. There is no pneumatic foramen : the compact wall of the 

 shaft of the femur is between one and two lines in thickness. As compared with the 

 femur of the Bustard, that of the Aptornis is thicker in proportion to its length, and 

 longer in proportion to the tibia ; and the ridge extending in the Bustard's femur from 

 the middle of the back part of the shaft towards the outer condyle, is not present in 

 that of the Aptornis. 



The tarso-metatarse (PI. III. figs. 5-8) measures three inches ten lines in length ; its 

 proportions in comparison with the tibia and femur resembling those of the Apteryx. 

 The ecto- and ento-condyloid cavities at the proximal end of the bone (PI. III. fig. 6) 

 are deeper than in Palapteryx or Dinornis, are more equal in size, and are more widely 

 separated by the intercondyloid tract and eminence : these modifications accord with 

 those of the distal end of the tibia figured in vol. iii. pi. 25. fig. 6. The intercondyloid 

 eminence is obtuse and relatively higher than in Dinornis or Palapteryx. The calcaneal 

 processes project further back and blend together in a smooth convex plate behind, 

 converting the groove for the flexor tendons into a foramen which is remarkable for its 

 width : its shape is shown in PI. III. figs. 5 & 6. Figure 7 shows another character of 

 the calcaneal prominence by which the Aptornis differs from the Dinornis and Palapteryx, 

 viz. in the absence of the buttress-like support formed in those genera by the posteriorly 

 projecting shaft of the mesometatarsal element. The back part of the shaft is even 

 and almost flat, the surface being broken only by one or two narrow intermuscular or 

 intertendinous ridges : just below the best-developed ridge near the inner side of the 

 bone, is the large and well-marked surface for the attachment of the metatarsal bone of 

 the hallux, i. The anterior surface of the tarso-metatarse is convex transversely, slightly 

 concave lengthwise : the distal end of the bone is so equally expanded, that both the 

 inner and outer sides show a nearly equal degree of concavity. A short groove on the 

 outer third of the fore part of the bone leads to the canal which pierces the confluent 

 parts of the outer and middle metatarsals, two lines above the space between the two 

 condyles of those bones : this canal answers to that which in the Notornis, Didus, 

 Diomedeea and many other birds, transmits the tendon of the adductor muscle of the 

 fourth toe (iv). The relative size and position of the condyles of the three coalesced 

 metatarsals are shown in figs. 5 & 8. The middle one advances further in front of the 

 others than in the Apteryv, Palapteryx and Dinornis : each condyle is impressed by a 

 well-marked median groove. 



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