332 PROFESSOR OWEN'S OBSERVATIONS ON THE DODO. 



The tarso-metatarsal bone (PI. XLIX. & L. fig. 1, mm) most resembles in its thick- 

 ness and general proportions that of the Eagles, especially the great Sea-Eagles {Hali- 

 aiitus, ib. fig. 2) ; it is much stronger than the tarso-metatarsus of any of the Vulturida, 

 or than that of the Cock, the Crax, or any of the Gallina or existing Struthionida ; the 

 stronger-footed species of Dinornis most resemble it in the general proportions of the 

 tarso-metatarsus, but greatly differ in the particular configuration of the bone, and in 

 the absence or feebler indication (as in Palapteryx) of the articulation for the metatarsal 

 bone of the back-toe. The relative size of this bone [ib. pm) is greater in the Dodo 

 than in any other known bird. The Eagles make the nearest approach to it in this 

 respect, as also in the shape of the back metatarsal {ib. fig. 2. pm), the breadth of its 

 distal end, and its peculiar twist backwards and outwards, so as to form a bridge or 

 pulley against which the flexor tendon of the hind-toe plays. 



This half-twist of the rudimental back metatarsal is feebly repeated in the GalUnce ; 

 but the bone is much less expanded at its lower articular end, especially in the Crax ; 

 whilst the more typical Gallinas are further distinguished from the Dodo by their spur. 

 The Apteryx is the sole existing Struthioid bird which possesses the hind-toe ; but it 

 is very much smaller than in the Dodo, and the supporting metatarsal bone is devoid 

 of the distal twist and expanded trochlea (ib. fig. 3, pm). 



The upper end of the tarso-metatarsus of the Dodo is remarkable for the great deve- 

 lopment of its calcaneal process (c), from which a strong ridge descends, gradually sub- 

 siding half-way down the bone. The posterior surface of the calcaneal process is broad, 

 triangular, vertically grooved, and perforated at its base. In the Eagle the correspond- 

 ing calcaneal process is a compressed subquadrate ridge, whose base of attachment is 

 not much longer than the obtuse end, and this is neither grooved nor perforated. In 

 the Cathartes Californianus the calcaneal process is thicker than in the Eagle, shaped 

 more like that of the Dodo, with a ridge descending upon the metatarsus ; but it has a 

 double groove behind. 



In the common Cock the calcaneal process more resembles that in the Dodo than the 

 Vulture's does, but it is not so broad. 



With regard to the first or i)roximal phalanx of the hind-toe, that of the Haliaetus is 

 larger and broader, especially at its base, stronger in proportion to its length, but longer 

 in proportion to the sustaining metatarsus. 



In the Vultures the proximal phalanx is not only longer in proportion to the meta- 

 tarsus, but is more slender than in the Dodo. The same bone is also longer and more 

 slender in proportion to the small supporting metatarsal bone in the Cock, the Crax, 

 and all other Gallina ; in fact, the Dodo is pecuhar among Birds for the equahty of length 

 of the metatarsus and proximal phalanx of the hind-toe. With regard to the three 

 trochlear extremities of the principal coalesced metatarsals, the middle one in all Gallina 

 is longer in proportion than in the Dodo, in which the inner one is nearly as long as 

 the middle one, the outer one being the shortest. In the Eagle the inner division is 



