PLATE III. 



Thalassina scoi'pionoidcs, nat. size (p. 19). 



<■. Peduncle of first antenna ; c" , coxal joint seen in section, showing the acoustic 

 apparatus ; c'", arrangement of hairs within the chamber ; c"" , one of the 

 hairs magnifier!. 



J. Siagon or mandible. 



e. First siagnopod. 



f. Second siagnopod, with one of the hairs of the mastigobranchial lash magnified in 



sections. 



