30 PROF. OWEN ON A FRAGMENT OF THE FEMUR 



as well as nearly the whole of the external or third trochanter, and of the deep and rough 

 depression below this trochanter. The orifice of the medullary artery is as conspicuous 

 in the femur of the Horse as in that of the Ox, on the outer and posterior part of the 

 middle of the shaft. 



The shaft of the femur in the Hog approaches more nearly in form to that of the 

 fossil than the bones with which it has just been compared, but no species of Sus is 

 now known to exist which presents a femur of equal size. The exterior linea aspera is 

 formed by a sharp angle which divides the outer from the posterior surface of the bone, 

 both of which surfaces are nearly flat in the Hog's femur ; the corresponding ridge, besides 

 being less sharply developed than in the fossil, is situated more on the posterior side 

 of the bone ; the anterior bifurcating ridge is wanting in the femur of the Hog. 



If the bone from New Zealand be compared with the femora of the Camel or Llama, 

 as great difi'erences present themselves as in the human femur ; the single linea aspera 

 on the middle of the posterior surface of the bone, and the perforation of the medullary 

 artery upon or near that ridge, forbid an approximation of these large Ruminants with 

 the fossil. 



The femur of the Kangaroo is at once distinguished by the longitudinal tuberosity 

 developed on the middle of the posterior part of the shaft. 



The/e»a(?- of the Dog, independently of its inferiority in size in the largest specimens 

 of this quadruped, difli"ers from the fossil in the absence of the anterior ridge, and in 

 the presence of the medullary canal near the middle of the posterior part of the shaft. 



In order that no reasonable ground might remain for doubting the accuracy of the 

 conclusion to which I have arrived in regard to the above-described bone, I have com- 

 pared it with the long bones of other Mammalia approaching it in size, notwithstanding 

 the improbability of their ever having found their way to the island of New Zealand. A 

 section of the shaft of a femur of the Grishj Bear, and of other large species of Urstis 

 corresponding in length and thickness with the fossil, does not give the expansion of 

 both extremities, and is moreover flatter antero-posteriorly : the same diiference is pre- 

 sented by the femur of the Lion and of other large species of Felis. The femora of both 

 the two last-cited genera of Mammalia are characterized by the aperture of the medul- 

 lary artery at the middle of the posterior part of the shaft. The femur of the Ouran 

 outang differs as much as any of the preceding Mammalia from the fossil. 



The differences between the fossil and the humeri and other long bones of the Mam- 

 malia above cited, are equally or more marked than in the femora. 



The texture of the bone, which affords the chief evidence of its ornithic character, 

 presents an extremely dense exterior crust varying from one to two lines in thickness : 

 this then rapidly degenerates into a lamello-cellular structure of from two to three hnes 

 in thickness. The lamellae rise vertically to the internal surface of the dense wall, are 

 directed obliquely to the axis of the bone, decussate, and intercept spaces which are 

 generally of a rhomboidal form, and from two to three lines in diameter. This coarse 



