120 INTRODUCTION TO 



planta,*) of the tarsus is frequently clothed with very 

 thickly set short hairs, forming a covering, which has 

 been called the foet-cuskion, (pulvillus). Other pe- 

 culiarities connected with this section of the leg 

 will appear when we come to examine it in the dif- 

 ferent orders. The number of the joints has been 

 found to afford very convenient means for forming 

 sub-divisions in the several primary sections, as they 

 are ascertained to be pretty uniform in nearly allied 

 species. Such as possess five joints in all the tarsi 

 are called pentamerous ; those having five joints in 

 the fore and middle legs, but only four in the hinder 

 pair, keteromerous ; when all the tarsi are four 

 jointed, tetramerous ; three jointed, trimerous ; two 

 jointed, dimerous ; and lastly, such as have only one 

 joint are termed monomerous. 



Owing to the fore legs frequently presenting a 

 structure different from the rest, adapting them for 

 becoming instruments of prehension, Mr. Kirby 

 thought they made so near an approach to arms> 

 that he applied to them that name. The five por- 

 tions described above, would, in this view, be re- 

 garded as analogous to the clavicle, scapula, humerus, 

 cubitus, and hand. Although many remarkable 

 appearances might be cited in support of this view, 

 yet it is obvious that the primary use of these limbs 

 as instruments of motion is never superseded, and 

 we are not entitled to bestow a new name on an 

 organ merely on account of a few slight modifications 

 of structure, or because it has been made subservient 

 to certain additional uses. It is not, besides, in all 

 cases the fore legs that supply the place of arms ; in 



