SKELETON OF THE MOLE. 197 



deltoid, pectoral, and other great burrowing muscles. 

 All the other bones of the fore-limb are as extremely 

 modified for fossorial actions. The olecranon expands 

 transversely at its extremity, and the back part of the 

 ulna is produced into a strong ridge of bone. 



The shaft of the radius is divided by a wide inter- 

 osseous space from the ulna, and the head of the radius 

 is produced into a hook-shaped process like a second 

 "olecranon." The carpal series consists of five bones 

 in each row — the scaphoid being divided in the first, and 

 a sesamoid being added to the second row ; moreover, 

 there is a large supplementary sickle- shaped bone, ex- 

 tending from the radius to the metacarpal of the pollex, 

 giving increased breadth and a convex margin to the 

 radial side of the very powerful hand, and chiefly com- 

 pleting its adaptation to the act of rapidly displacing the 

 soil. The phalanges of the fingers are short and very 

 stronof: the last are bifid at their ends for a firmer attach- 

 ment of the strong claws. Little more of the hand than 

 these claws, and the digging or scraping edge, projects 

 beyond the sheath of skin enveloping the other joints, 

 and connecting the hand with the trunk. 



The common position of the arm-bone is with its distal 

 end most raised. The fore-arm, with the elbow raised, is 

 in the state between pronation and supination, the radial 

 side of the hand being downwards, and the palm directed 

 outwards. The whole limb, in its position and structure, 

 is unequalled in the vertebrate series as a fossorial instru- 

 ment, and only paralleled by the corresponding limb in 

 the mole-cricket {Gryllotalpa) amongst the insect-tribes. 



Ko impediment is offered by the hinder parts of the 

 body or limbs when the thickest part of the animated 

 wedge has worked its way through the soil. Tlie pelvis 



17-^ 



