208 Analyses of Booh. [MAttClf, 



way. They are also each of them divided longitudinally on 

 their concave side by three or four slight ridges ; so that, 

 though highly polished, their surface is not absolutely smooth ; 

 and thus being concave and uneven, they are more apt to retain 

 particles of the excavated earth ; which, by filling up the inden- 

 tations of the claws, would necessarily impede their due action. 

 To obviate this inconvenience, an exceedingly curious instru- 

 ment is attached to the upper part of the concave surface of this 

 member : this instrument consists of two claws, closely resem- 

 bling those already described, having by their side a small 

 brush as it were, which terminates in two spines. These two 

 claws, together with the piece bearing the spines, arise from a 

 single piece, or handle, which is articulated in such a manner, 

 as to move in a plane parallel to that in which the four claws 

 are placed : but in a direction opposite to that in which they are 

 moved : they are also placed in such a manner that their points 

 and cutting edges are opposed to the points and cutting edges 

 of the true claws ; and hence the two parts, thus opposed to 

 each other, act like the blades of a pair of shears. When first 

 I considered this mechanism, and remembered that in the loca- 

 lities where I had found the animal, the earth was frequently 

 traversed by fibrous vegetable roots, which must necessarily 

 retard its progress, I supposed that it used this instrument as a 

 pair of shears to cut through those fibres. It is Rbsel's 

 opinion, however, that the instrument is intended to clear the 

 true claws of the dirt that may from time to time collect upon 

 and clog them ; and unless both opinions be true, Rosel's 

 appears the more probable. But I have not yet concluded the 

 account of the curious mechanism of this member; for the 

 brush which has just been described, has only such an extent of 

 motion as enables it to clear the two uppermost claws, or at most 

 the three uppermost : the two lowermost howeyer may effec- 

 tually be cleared by a kind of feathered spui-, which, arising 

 from the further extremity of the joint answering to the femur, 

 proceeds directly towards the lowest part of the burrowing 

 instrument, and is easily made to sweep over the surface of the 

 two last claws by bending the intermediate joint, the only differ- 

 ence in its mode of action being, that it passes over their inner 

 instead of their outer surface. 



" The middle pair of legs, which are the smallest of the three 

 pairs, arises from the under part of the first segment of the abdo- 

 minal division : they pass out from the body at right angles to 

 the abdomen, and usually are seen in that direction whether the 

 animal be in motion or at rest. They consist each of four parts ; 

 a very short coxa, a femur and tibia nearly equal in length to 

 each other, and a tarsus, which consists of two long and an 

 intermediate short joint; the last joint terminated by two curved 

 spines. There are several sharp, hard, straight spines near the 



