144 PROFESSOR OWEN ON THE GENUS DINORNIS. 



A small portion of the upper ridge of the great trochanter has been broken off : when 

 entire, the femur of the Din. gracilis presents the average length of that of the Din. 

 struthioides ; but it is more slender in proportion, the head is smaller, and is supported 

 by a better marked constriction or neck, especially at its under part. The upper plat- 

 form of the trochanter is narrower, the anterior border of the trochanter not being 

 extended so far forwards and outwards. The angle between the upper and fore surfaces 

 of the trochanter is a right one, and they meet at a sharp ridge. The rough oval 

 surface between the head of the femur and the base of the trochanter is smaller than 

 that of the Din. struthioides. The outer irregular surface of the trochanter is of much 

 less breadth in the Din. gracilis. The muscular impressions at the sides of the shaft 

 meet and form a longitudinal ridge along the back part of the middle third of the shaft : 

 they are separated by a tract of half an inch in the Dinornis struthioides, and terminate 

 below in two tuberosities. The corresponding ridge formed by the meeting of the vasti- 

 muscles along the fore part of the shaft is shorter in Din. gracilis than in Din. stru- 

 thioides. 



The most marked distinction, however, is presented by the distal extremity of the 

 bone, which is not only relatively less expanded in the Din. gracilis, but tbe rotular 

 groove is narrower, and is bounded laterally by condyloid eminences of more nearly 

 equal length ; the external one not rising so high up, nor describing the sigmoid curve 

 in descending, as in the Din. struthioides. The rotular groove in the Din. gracilis is 

 impressed by a transversely oval rough depression, at its upper part, with sharp lateral 

 borders, which depression does not appear in any of the femora of the Din. struthioides. 

 The popliteal space is triangular and better defined in the Din. gracilis ; the fibular 

 groove is shorter and less angular, and the rough deep pit above it is smaller. The 

 tibial surface on the inner condyle is relatively smaller. 



Tibia. 



Tbe same character is repeated on the proximal end of this bone, where the surface 

 apphed to the inner condyle is absolutely smaller than in the Din. struthioides, although 

 the entire bone, as shown in the subjoined admeasurements, is longer in the Din. gracilis : 

 it is also, as the name of the species implies, more slender in proportion to its length. 



This bone (PI. XLII. fig. 1) was obtained from beneath a sandy deposit, about two 



feet below the surface, at a locality between Wanganui and Turakiua, North Island of 



New Zealand, by the Rev. Mr. Taylor. 



D. gracilis. 

 in. lin. 



The entire length of the bone is 23 6 



The transverse breadth of its proximal end . . .5 



The transverse breadth of its distal end . . . 2 10 



The circumference of the middle of the shaft . . 4 6 



The fibular ridge extends down the shaft ... 96 



