364 PEOPESSOE OWEN ON THE GENUS DINOKNIS, 



oval form, 1 inch 9 lines in length, 7 lines in extreme breadth, and is divided from the 

 back part of the articular surface of the outer trochlea (iv) by a smooth tract about 

 4 lines in breadth. A narrow, oblong, rough tract at the proximal part of the shaft 

 behind the ectometatarsal ridge (ib. fig. 2, k) may serve also for gastrocnemial insertion ; 

 but it is divided from the loveer ectogastrocnemial tract by a smooth surface of the mid 

 part of the metatarsal, about an inch and a half in extent in one instance, and two 

 inches in the specimen figured in PI. LVIII. The narrow tract from the entogastro- 

 cnemial tuberosity {g) is more feebly marked, if it be discernible, in Dinornis crassus. 

 The ectogastrocnemial surface is also less defined, and is continued upwards as a more 

 or less conspicuous ridge to within a few lines of the ectometatarsal rough surface in 

 Dinornis crassus. 



The fore part of the en to trochlea (tig. 1, ii) is broader relatively to the hiad part in 

 Dinornis gravis than it is in Dinornis crassus. The outer side of the fore part of the 

 ectotrochlea (iv) is more convex or tuberous, and is less defined from the ectotrochlear 

 fossa than in Dinornis crassus. 



The interspaces of the trochlece are narrower in Dinornis gravis ; and this character 

 is the more easily seized, inasmuch as the breadth of the three troohlese is almost 

 the same in the two species, notwithstanding the difierence in the length of the 

 metatarsi. 



Dinornis gravis had a stronger and stouter foot, relatively, than Dinornis crassus ; 

 and the muscular force working it was more powerful, as is indicated by the insertional 

 ridges and tracts {g,y,x). 



In a metatarsus of Dinornis crassus, 8 inches 6 lines in length, the greatest breadth of 

 the mid trochlea is 1 inch 8 lines ; in a metatarsus of Dinornis gravis 7 inches 9 lines 

 in length the greatest breadth of the mid trochlea is 1 inch 10 lines. 



The general characters of the bone, with the disposition and aspects of the distal 

 trochlea, are much alike in the two species ; but the difi'erences above defined impress 

 me with the conviction that ornithologists would find the birds to which the metatarsi 

 of Di)i. crassus and Din. gravis belonged, if they had them entire to compare, to be 

 distinct species. 



The number of the living species of Casuanus which have of late years been dis- 

 covered in detached remnants of the great Australasian continent, show much more 

 striking differences in plumage and dermal appendages than could have been suspected 

 from any differences which are discernible in the bones of the legs ; and these differences, 

 when most distinct, are less marked than those above demonstrated in the metatarsals 

 of the species of Dinornis which least differ in general size. 



The tibia of Dinornis gravis (PI. LIX.), in comparison with that of Dinornis crassus, 

 which it most resembles, has a stronger or thicker shaft in proportion to its length ^ 

 The character of the metatarsal bone of Dinornis gravis is here repeated, but in a minor 



' See Table of Admeasurements, p. 371. 



