EXPLANATION OF PLATE V. 



Figuke 20. — Caprella geometrica Say, (p. 567;) lateral view, enlarged about three 

 diameters. 



21. — Sphseroma quadridentata Say, (p. 569 ;) dorsal view, enlarged five diam- 

 eters. 



22. — Idotea caeca Say, (p. 569 ;) male ; dorsal view, enlarged three diameters. 



23. — Idotea irrorata Edwards, (p. 569 ;) male ; dorsal view, enlarged two 

 diameters. 



24. — Idotea robusta Kroyer, (p. 569;) male; dorsal view, enlarged two diam- 

 eters. 



(Figures 20, 21, 23, and 24, were drawn \>y J. H. Emerton; figure 22 by O. Harger.) 



