1826.] Philosophical Transactions for 1825, Part II. 207 



to system were I to describe the parts composing these legs by 

 the terms strictly indicative of the order of their succession ; for 

 thus that part which answers so eminently to the character of a 

 hand must be called the tibia. I shall beg leave therefore to 

 state principally that the fore leg of this insect consists of three 

 main parts, with a lateral appendage attached to the last of 

 them. The two first of the three parts bear some general resem- 

 blance to the claw of the crab ; being short and thick, for the 

 purpose of affording room for powerful muscles, intended to 

 move the last part; which is the immediate instrument employed 

 by the animal in burrowing. 



" It might I think be asserted, without the fear of contradic- 

 tion, that throughout the whole range of animated nature, there 

 is not a stronger instance of what may be called intentional 

 structure, than is afforded by that part of the mole-cricket 

 which I am now to describe. 



" The natural and constant position of this member is worth 

 noticing ; the palm, as it may be called, facing outwards, and 

 the claws ranging not in a horizontal but a vertical line, so that 

 none of them but the lowermost, and not even this necessarily, 

 touches the surface on which the animal is walking. Accordingly 

 the insect does not make much use of its fore-legs in walking ; 

 and, if irritated, it advances towards you with these legs elevated, 

 in a menacing attitude as it were ; not unlike the corresponding 

 attitude of the insect called the mantis. The form of the hand 

 is that of a triangle ; the base of which is formed by the four 

 claws, while the apex is situated at the joint connecting this with 

 the preceding part ; by which form and disposition two important 

 objects are gained ; for the joint is thus capable of a much 

 greater extent of motion than it could have possessed, had the 

 articulating surface been more than a mere point; and at the 

 same time, the greater extent of the base enables it to act with 

 more powerful and more rapid effect than could have been 

 otherwise produced. The four claws, which form this base, 

 constitute the proper burrowing instrument ; and their shape 

 and structure are beautifully adapted to the purpose ; for instead 

 of being covered with down or hair, like all the rest of the limb, 

 they are hard, and have a perfectly polished surface ; doubtless 

 in order to prevent as much as possible the adhesion of the earth 

 through which the animal is to make its way; they have each of 

 them sharp but strong points, which proceeding from a broad 

 base are thus rendered more eftectual. In each also of the 

 claws one of the edges is sharp, while the other is comparatively 

 blunt ; and all the cutting edges, as also the terminating points, 

 are directed downwards. Their outer surfaces are slightly con- 

 cave both in the longitudinal and transverse direction ; so that 

 all together they form a scoop as it were, by which the earth 

 that has been scraped off by the points is moved out of the 



