Table 4. Comparison of nemas with other animals. (Cont. p. 199). 



Group 



Annelida 



Exoskeleton 



Ectodermal 

 Epithelium 



Somatic 

 Musculature 



Metamerism 



Body cavity 



Cuticle annu- 

 lated 



Chords and 

 columnar 



External cir- 

 cular; internal 

 longitudinal; 

 2 layers 



True internal 

 metameric ganglia 



Coelome filled 

 with fluid 



Nemertea 



Do. 



Do. 



Ext. cir- 

 cular; int. 

 longitudinal; 

 int. circular; 

 int. longitu- 

 dinal layers 



Pseudometamer- 

 ism of gonads and 

 gut pockets 



RhjTichocoelome 

 and parenchyma 



198 



