EXPLANATION OF PLATE IV. 



Figuee14. — Orchestia agilis Smitli, (p. 555;) male; lateral view, enlarged five di- 

 ameters. 



15. — Gammarus ornatus Edwards, (p. 557 ;) male ; lateral view, enlarged two 

 diameters. 



16. — AmpMtlioe maculata Stimpson, (p. 563 ;) male ; lateral view, enlarged 

 two diameters. 



17. — Ampelisca sp., (p. 561 ;) lateral view, enlarged five diameters. 



18. — Cerapus rubricornis Stimpson, (p. 565;) female; lateral view, enlarged 

 five diameters; and hand of the second pair of legs of the male, en- 

 larged the same amount. 



19.— Unciolairrorata Say, (p. 567;) male; dorsal view, enlarged six diameters. 



(All the figures were drawn by J. H. Emerton and S. I. Smith.) 



