i8o 



Microscopical Essays. 



The naiatorii, thofe that ferve as oars for fwimming. The 

 thighs of the faltatorii are remarkably large, by which means they 

 have considerably more ftrength and power for leaping. The 

 feet of the natatorii are flat, and edged with hairs ; thus have a 

 proper furface to ftrike againft the water, as in the dytifcus, 

 notone&a, &c. 



Such feet as have no claws are termed mutici. The chela?, 

 or claws, are an enlargement of the extremity of the fore feet, 

 each of which is furnifhed with two lefler claws, which aci like a; 

 thumb and finger, as in the crab. 



The under part of the feet, in fome infects, is covered with a 

 kind of brum or fponge, by which they are enabled to walk with 

 eafe on the moft polifhed fubftances, and in fituations from which 

 it would feem that they muft neceflarily fall. 



** They tread the ceiling, an inverted floor, 

 And from it's precipice depend fecure." 



Many infects can only move the thigh in a vertical direction ; 

 while others can move it in various directions. The progreflive 

 motion of infefts, and the various methods employed to effect it, 

 will be found a very curious and important fubject, and well 

 worthy the attention of the natural hiftorian. The mechanic will 

 not find it loft labour if he beftows fome time on the fame fub- 

 jecl. Very little has been done on this head, and that principally 

 by Mr. de Reaumur, in lis excellent Memoires ; and by M. 

 Weifs, in a memoir publifhed in the Journal de Phyfique for 

 1771. The reader may alfo confult Borelli de Motu Animalium. 



Motion, 



