IO 



A BIOLOGY OK CRUSTACEA 



ii 



L* 



MOUTH 



Fig. 9. Darwin's diagram of the relation between the anatomy 

 of a stalked barnacle (Lepas) and a prawn (Lucifer). An 

 important feature to note is that in Lucifer the preoral part of 

 the head is elongated. Actually this comparison is super- 

 ficial, because in the barnacle the internal organs become 

 reorganised so that the ovary lies in the stalk. 



BASES OF 

 THORACIC UMBS 



Fig. 10. Lepas australis (Cirripedia), with the right half of 



the mantle removed. The actual length of the part shown 



is about 2 cm.; the stalk extends to about 5 cm. 



