Smithsonian Report, 1893. 



Plate XXX. 



WS" 





■^•Sk-^*' 



Zoological Station at St. Andrews, Scotland. 



Dutch Zoological Station at the Helder. 



Fistire from Tijdscbr. d. Ned. Dierk. Vereeii. 5 .Tuli, 1890. 



