EXPLANATION OF PLATE V. 



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

 diameters. 



21. Sphreroma quadridentata Say, (p. 569 ;) dorsal view, enlarged live diam- 

 eters. 



22. Idotea creca 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 by J. H. Emerton ; figure 22 by O. Harger.) 



