58 THE ROYAL SOCIETY OF CANADA 



both ends, and closely applied to metacarpal IV. Distal articular 

 surface almost flat and sub-quadrangular. Length 225 mm. 



Metacarpal IV is somewhat heavier than III and flattened 

 internally for close union with the corresponding surface of III. 

 Greatest width near proximal end transversely (65 mm.). The antero- 

 posterior width here is 35 mm. Distally the greatest width is antero- 

 posterior (50 mm.). Both articular surfaces are convex. Length, 

 same as metacarpal III, 225 mm. 



Metacarpal V is a much shorter and smaller bone, divergent, 

 and with no trace of close approximation to metacarpal IV. It is 

 somewhat twisted and greatly expanded proximally. The distal end 

 is small and obliquely convex, indicating great power of flexion and 

 possibly prehensile ability in this digit. The proximal articular sur- 

 face is slightly concave and oval, 58 mm. by 40 mm. Length of bone, 

 83 mm. 



The arrangement of the metacarpals presents no feature of strik- 

 ing difference from the generally accepted anatomy of the manus. 

 The phalanges on the other hand are very remarkable and differ in 

 important details from any manus hitherto described. 



The phalangeal formula is as follows: 



Digit II with three phalanges, the third a hoof. 



Digit III with three phalanges, the third a hoof. 



Digit IV with three phalanges, the last small and probably 

 carrying a nail. 



Digit V with four phalanges, the last a small evenly ovoid bone. 



The first phalanges of digits II, III and IV are almost equal 

 in length (55-65 mm.), and are expanded at both ends. Phalanx 

 IP is excavated externally and closely applied laterally to the distal 

 end of metacarpal 1 11.^ 



The second phalanx in digits II and III is very remarkable, 

 being in both cases a small triangular or wedge-shaped bone. The 

 articular surface extends over the edge of the wedge. This fact, 

 the position of the bones in the matrix, and the character of the 

 articulating surfaces, point clearly to the position of these bones as 

 external as shown in Figures 12 and 13. This disposition of these 

 peculiar bones must of necessity throw the unguals inward. A wedge- 

 shaped phalanx in one digit has been recorded previously; this seems 

 to be the first instance of the occurrence of two. 



^"External" and "intermi" are used with respect to the axis of the body, 

 not of the hmb. 



