8 THE LIFE OF CRUSTACEA 



fore, as the cephalothorax. It is necessary to bear in 

 mind that the parts of the body to which the names 

 head, thorax, and abdomen, are applied in Crustacea 

 are by no means exactly equivalent to those which 

 bear the same names in Insects, for example, and 

 that, beyond a rough similarity in position, they 

 have no sort of relation to the parts so named in the 

 body of a vertebrate animal. 



There are altogether twenty pairs of appendages 

 attached to the body of the Lobster. In front of the 

 head are the stalked eyes (of which the nature will be 

 discussed later) and two pairs of feelers the anten- 

 nules and antenna (sometimes called the first and 

 second antennae). Near the mouth on the under- 

 side of the head are three pairs of jaw-appendages 

 the strong mandibles and the flattened, leaf-like 

 maxilhdce and maxilla. Following these are the 

 appendages of the thorax, of which the first three 

 are intermediate in form between the true jaws and 

 the legs, and are therefore termed foot-jaws, or 

 maxillipeds. The remaining five pairs of thoracic 

 limbs are the legs, the first pair forming the large 

 and powerful pincer-claws, or chelipeds, while the 

 others are the walking legs. The six pairs of 

 swimmerets on the abdomen have already been 

 mentioned. 



If one of the somites of the abdomen be separated 

 from the others, it will be seen (Fig. 2) to consist of 

 a shelly ring, to which the two swimmerets are 



