THE LOBSTER AS A TYPE OF CRUSTACEA 7 



later, on the same plan as the swimmerets, it is 

 concluded that this part also is built up of somites, 

 which have become soldered together. That this 

 conclusion is correct is shown by comparison with 

 some of the lower Crustacea in which this part of 

 the body is divided up into eight separate somites, 

 like those of the abdomen, each carrying, in place of 



Cefihahthorax 



Caranace ** 



Cervical groove ' WTTUm 



Antennule 



Anlenna 



Walking legs 



FIG. i THE COMMON LOBSTER (Homarus gammarus), FEMALE, 

 FROM THE SIDE. (From British Museum Guide.) 



the swimmerets, a pair of walking legs. In front of 

 these eight somites, forming what is called the thorax, 

 is the head a part of the body which is never, in 

 any Crustacean, broken up into distinct somites, but 

 which, since it carries five pairs of appendages, must 

 consist of at least five somites. The part of the 

 body covered by the Lobster's carapace includes 

 both the head and the thorax, and is known, there- 



