112 



ME. C. W. AXDEETVS 0>' EEMAINS OP JTYOEXIS [Feb. 6, 



(Plate XIV. figs. 3 & 4), both unfortunately incomplete at the 

 upper end. The dimensions of these bones are : — 



Length 



Width of distal end 



Width of shaft at narrowest 

 point 



Circumference of shaft at nar- 

 rowest point 



Shortest antero-posterior dia- 

 meter 



^. titan. 



cm. 

 800 



170 



10 



20-7 

 4-5 



^. maximus. 



cm. 

 640 



13-5 



15-5 



SI. hildebrandti. 



cm. 

 48-5 



8-2 



11-0 



The shaft is slightly curved, the inner border being concave. 

 The flattening of the lower part of the anterior face, characteristic 

 of the genus, is here more strongly marked than in the other 

 species, and extends rather farther up the shaft. This flat surface 

 is bounded on either side by a ridge, that on the inner side being 

 the stronger ; these sharply separate the anterior from the lateral 

 surfaces, A^hich with the posterior form a continuous curve from 

 side to side, rather flattened behind, especially towards the lower 

 end of the bone. The lateral surfaces are also flattened and rough 

 in the same region. A liaea asjicra runs obliquely across the upper 

 part of the anterior face from the proenemial crest to the inner 

 border, which it reaches about 32 cm. above the lower end of the 

 bone. In the other species of ^pyornis of which the tibio-tarsus 

 is known, as well as in Dinomis, this ridge takes a more longitu- 

 dinal course and only reaches the inner border a httle above the 

 condyles. Immediately above the latter is a short ridge running 

 up the face of the bone and having at its lower end a rugose 

 tubercle. Between this ridge and the inner border is the groove 

 for the extensor tendons of the digits, deep at its lower end and 

 dying away as it is traced upwards. As in the other species there 

 is no ossified extensor bridge. About 2-5 cm. above the outer 

 condyle is a large foramen for the passage of a blood-vessel into 

 the bone. 



The condyles have the form characteristic of the genus. The 

 inner is the larger and projects more forward. The intercondylar 

 surface is only sUghtly depressed and, though faintly convex from 

 side to side, does not form a distinct ridge between the condyles 

 such as is figured by Bui-ckhardt in ^. hildebrandti. The lateral 

 surfaces of the condyles have very deep pits for the insertion of 

 ligaments, that in the outer beiug 2-5 cm. deep. Behind these 

 pits are large rugose tuberosities. The surface for the fibula 

 closely resembles that of ^. madimus. 



The wall of the bone is very hard and compact, and is about 



