SKELETON OP PHOEOBHACOS INPLATTJS. 83 



In Gms the metatarsus differs in the complication of the hypotarsus and the position 

 of the inner (2nd) trochlea, which is high up and much deflected backward. 



In Psophia there is a close canal in the hypotarsus, otherwise the bone is much 

 like the fossil. 



In Cariama the metatarsus in most respects closely resembles that of PJiororJiacos, 

 but it is proportionately more slender, and at its distal end the lateral trochlea? 

 (particularly the inner 2nd) are less reduced. The metatarsus of Ciconia is similar in 

 many points, but at the proximal end the hypotarsus is longer, its crests much more 

 prominent, and it is situated further below the glenoid surfaces than is the case in 

 PhororJiacos. At the distal end the chief difference is that the lateral trochlea? are larger 

 in proportion to the median one. 



In most Accipitrine birds the metatarsus is widely different, both in the form of the 

 hypotarsus and the deep excavation of the hinder surface of the shaft for the various 

 muscles of the toes and the arrangement of the trochlea?. Serpentarius, however, has 

 undergone such modification in correlation with its terrestrial habits that it approaches 

 PhororJiacos very much more closely than do the rest of the group : this is chiefly the 

 result of the elongation of the shaft and the alterations in the form of the talon and in 

 the arrangement of the trochlea?. Nevertheless, there are several points, such as the 

 almost complete absence of an intercondylar tuberosity, in which it differs widely 

 from the fossil. 



The dimensions of the metatarsus are : — mm 



Width at proximal end 47 



„ at distal end 44 



„ of middle trochlea 19 



Only one of the phalanges of the hind foot belonging to the skeleton above described 

 is preserved, but there is a nearly complete left pes of another individual of the same 

 species. In this it is seen that the hallux was well developed and terminated in a strong 

 hooked claw : the metatarsal articulates with the tarso-metatarsus by a simple knob, 

 and terminates distally in a trochlear surface with a deep pit for ligament on its outer 

 side. The total length of this toe is about 53 mm. In the second digit there are, as 

 usual, three phalanges, the terminal (3rd) one being sharp-pointed and slightly hooked; the 

 remaining two, though shorter than the phalanges of the middle digit, are nearly as stout. 

 The lengths of the phalanges are: 1st, 31 mm. ; 2nd, 32 mm. ; 3rd (ungual), 36 mm. ; the 

 total length of the toe is about 93 mm. The middle toe consists of four phalanges, the 

 first of which is nearly as long as the two proximal phalanges of the second digit together ; 

 both it and the two succeeding digits are somewhat compressed from above downward. 

 The ungual phalangeal is a powerful hooked claw. The lengths of the phalanges are : 

 1st, 55 mm. ; 2nd, 38 mm. ; 3rd, 27 mm. ; 4th (ungual), 44 mm. 



Of the inner toe only the ungual and one of the other phalanges is preserved; the 

 length of the former is about 27 mm. 



