PLATE I. 



Diapiomus castor. 



[1. Male, antennae not yet fully developed, showing shell, gland, heart, reproduct« 



•' ive, alimentary and muscular systems. 

 2. Female, antennae and appendages removed except fifth feet. 

 3 and 4. Nauplius stage. 



5. Male foot of fifth pair, (a) " thumb " of larger branch. 



6. Female foot^of fifth pair. 



7. Mouth parts etc. 



