536 BIOLOGY. 



3266. Since the limbs of the Insect are only the lateral 

 filaments of the Worms, which have become hard and 

 consequently hollow ; they are as such not to be termed 

 true feet, but are only to be compared with branchial 

 arches or ribs; a step by which their greater number 

 also admits of being understood. They are not to be 

 compared with our feet, but unto the toes, which have 

 been separated from each other as far as the rings of the 

 body. The Crab has properly five thoracic and five 

 abdominal toes. All its thoracic feet taken together 

 are only equivalent to our hand. 



The feet of the higher animals are only Insect-feet 

 connate or coalesced. 



3267. In other respects they already typify or pre- 

 figure true limbs, as well from their position as by the 

 division of their joints. A perfect beetle's foot divides 

 exactly like the limb of Man, into femur, patella, tibia, 

 tarsus, and phalanges. These parts of the leg must not, 

 however, be so absurdly divided and named, as has 

 hitherto been unfortunately the case in our systems, 

 where the femur has been called coxa, the patella tro- 

 chanter, the tibia femur, while the toes have been lumped 

 under the name of tarsus. (Ed. 1st, 1811. 3087.) 

 The regular number of the toes or tarsal joints is five, 

 so that they correspond to our digital phalanges, to the 

 metacarpal, and the anterior carpal bone. 



3268. The wings are the branchiae of the Mollusc that 

 have been set free ; they are placed therefore upon the 

 back and are four in number. In many Insects there is 

 still a pair of wing- like scales in front of the four wings, 

 as in some Lepidoptera. They perhaps correspond to 

 the shells of Molluscs, are branchial opercula. 



It is only from this point of view that the structure of 

 Insects admits of being fully understood ; and apart from 

 this it is absolutely devoid of all analogy. Thus it is pos- 

 sible for only six legs to take their origin from the thorax 

 in the direction downwards, and nevertheless for there still 

 to be wings upon the dorsum or back. The wings of Birds 

 are by no means homologous to the alar appendages of 



