PLATE LVI. 



Benthesicymus iridescens (p. 335). 



Fig. 1. Outer branch of sixth pleopod ; arterial vessels, red ; venous, blue ; nerve- 

 filaments, yellow; muscles, brown. 



„ 2. Ventral nerve-cord of same. 



Eucopia australis. 

 ,, 3. Ventral nerve-cord. 



Sergestes atlanticus. 

 „ 4. Arrangement of muscles in the sixth somite of the pleon. 



