ROOM II. BONES OF THE DINORNIS. 115 



breadth of the rotular cavity, are the chief generic characters 

 of the femur of the Dinornis. 1 The largest femur is sixteen 

 inches long, and the shaft seven inches and a half in circum- 

 ference. 



Tibia and Fibula. Table-Case 15. The Tibia, even in 

 the species in which it is of great length, is relatively 

 thicker and stronger than in the Ostrich or Cassowary. It is 

 distinguished from the corresponding bone in the Struthi- 

 onidse by an oblique bony process that extends across above 

 the distal trochlea, on the anterior and inner side of the bone, 

 and forms a canal for the extensor tendon, as in the Bustard. 

 The longest specimen of a tibia is nearly three feet in length, 

 and the circumference of the middle of the shaft is six inches 

 and a half. The tibia is strongly marked by a ridge for arti- 

 culation with the fibula, which is a long and very slender 

 bone extending two-thirds down the shaft of the leg-bone, and 

 entirely free. My son collected several very large fibula 

 belonging to Dinornis and Palapteryx ; and many that are 

 referable to other and much smaller birds. It is remarkable 

 that such delicate fossil bones (as those in the table-cases) 

 should have arrived from the Antipodes in so perfect a state. 



Tarso-metatarsals. Table-Cases 15, 16, 17. The tarso- 

 metatarsal (shank-bone) is so named because it is formed by 

 the coalescence of the tarsus and the three primary metatar- 

 sals into a single bone, which at the distal end is divided into 

 three trochlear articulations for the corresponding number of 

 toes. In the Dinornis this bone is remarkably strong and 

 broad, and of great width at the distal or trochlear extremity. 

 The proximal end has two concavities, the inner one the 

 deepest, for articulation with the tibia. There are no indica- 

 tions of a posterior toe : the Dinornis being a tridactyle, or 

 three-toed bird. 



In the unique specimens of the entire series of bones of 

 both feet with the two metatarsals of the same individual of 

 Dinornis robustus, collected by my son at Waikouaiti, there 

 is not the slightest trace of an articulating surface for a hind 

 toe. 



The ossification of the metatarsals in the Dinornis appears 

 not to have been perfected till a late period, as in the existing 



1 See " Zool. Trans." vol. iii. p. 248. 



