EXPLANATION OF PLATE V. 



Figure 20.— Caprella o-eometrica Say, (p. 5G7;) lateral view, enlarged about three 

 diameters, 



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

 eters. 



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



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

 diameters. 



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

 eters. 



(Figures 20, 21, 23, an<l 24, were drawn by J. H. Emerton ; figure 22 by O. Harger.) 



